DEPARTMENT  OF  THE  INTERIOR 
UNITED  STATES  GEOLOGICAL  SURVEY 

GEORGE  OTIS  SMITH,  Dikectok 


Bulletin  432 


SOME  ORE  DEPOSITS  IN  MAINE 


AND 


THE  MILAN  MINE,  NEW  HAMPSHIRE 


BY 


WILLIAM  H.  EMMONS 


QE 


-B9 


WASHINGTON 

GOVERNMENT     PRINTING     OFFICE 

1910 


DEPARTMENT   OF   THE   INTERIOR 

UNITED   STATES   GEOLOGICAL   SUliVEY 

GEORGE  OTIS  SMITH,  Director 


Bulletin  432 


SOME  ORE  DEPOSITS  IN  MAINE 


AND 


THE  MILAN  MINE,  NEW  HAMPSHIRE 


WILLIAM  H.  EMMONS 


WASHINGTON 

GOVERNMENT    PRINTING    OFFICE 

1910 


YiQ  • 


^^'^ 


CONTENTS. 


Pa?e, 

Introduction 7 

General  statement 7 

Acknowledgments 8 

Bibliography 8 

Geography 10 

Mining  development 10 

Production  of  metals 11 

Geology 11 

Sedimentary  rocks 11 

Ellsworth  schist 11 

Islesboro  formation 12 

Battle  quartzite 12 

Penobscot  formation 12 

Ames  Knob  formation 12 

Perry  formation 13 

Igneous  rocks 13 

Castine  formation 13 

North  Haven  greenstone 13 

Thorofare  andesite 14 

Vinalhaven  rhyolite 14 

Granite 14 

Diorite 15 

Basic  lava  flows 15 

Basic  dikes 15 

Ore  deposits 15 

Classification 15 

Deposits  older  than  regional  metamorphism 15 

Distribution  and  character ^. 15 

Metamorphism 18 

Origin 20 

Deposits  associated  with  granite  intrusions 20 

Fissure  veins 20 

Molybdenite  and  lead  deposits. .  .A^»*.  i^^ HTl. 21 

Deposits  associated  with  diabase  and  trap 22 

Mineralogy 22 

Distribution  of  outcrops 24 

Oxidation  and  secondary  enrichment 25 

Future  of  the  mines 26 

Lead,  zinc,  and  silver 26 

Copper 27 

3 


4  CONTENTS. 

Ore  deposits — Continued.  Page- 
Summary  of  geologic  events  as  related  to  ore  deposits 27 

Pre-Cambrian  and  Cambrian  time 28 

Silurian  time 29 

Devonian  time 29 

Quaternary  time - 30 

Descriptions  of  mines 30 

Mines  of  Hancock  County 30 

General  statement 30 

Douglas  mine 31 

Twin  Lead  mine 32 

Blue  Hill  mine 33 

Stewart  mine 33 

Mammoth  mine 34 

Owen  mine 34 

Owen  lead  prospect 34 

Granger  mine 35 

Weil  Freddie  mine 35 

Tapley  mine 35 

Eggemoggin  mine 36 

Deer  Isle  mine 37 

Cape  Rozier  mine 38 

Hercules  mine 38 

Jones  &  Dodge  mine 38 

Emerson  mine 39 

Sullivan,  Waukeag,  and  Pine  Tree  mines 39 

Gouldsborough  mine -  - 40 

Franklin  Extension  mine ".  ".  -  -  - 41 

Copperopolis  mine -  - "? 41 

Catherine  Hill  molybdenum  mine 42 

Mines  of  Washington  County 43 

General  statement - 43 

Cherryfield  mine 43 

Lubec  lead  mine 44 

Denbow  Point  mine 45 

Prospects  in  Pembroke 46 

Cooper  mine 47 

Mines  in  Somerset  and  Oxford  counties 48 

Robinson  mine 48 

Mount  Glines  deposits 49 

Milan  mine,  New  Hampshire 50 

General  statement 50 

Geology 52 

Minerals  of  the  ore 54 

Ore  bodies 55 

Summary  of  the  genesis 59 

Index 61 


ILLUSTRATIONS. 


Page. 
Plate    I.  A,  Photomicrograph  of  schistose  ore  from  Deer  Isle  mine;  B,  Pho- 
tomicrograph of  thin  section  of  ore  from  Owen  lead  prospect 20 

II.  Geologic  map  of  mineralized  area  of  Blue  Hill 30 

III.  A,  Polished  surface  of  schistose  ore  of  Milan  mine;  B,  Photomicro- 
graph of  molybdenite  ore  from  Catherine  Hill 42 

Figure  1.  Outline  map  of  southern  Maine 7 

2.  Stringer  of  contorted  pyrite  in  contorted  rhyolite  near  the  Tapley 

lode 16 

3.  Quartz-pyrite  veinlet  leading  off  from  Twin  Lead  lode 17 

4.  Plan  of  part  of  the  115-foot  level,  Milan  mine 17 

5.  Ore  from  Twin  Lead  mine,  Blue  Hill 18 

6.  Thin  section  of  ore  from  Milan  mine 19 

7.  Thin  section  of  schistose  ore  from  Deer  Isle  mine 20 

8.  Ore  from  Sullivan  mine 21 

9.  Brecciated  diabase  cut  by  quartz  and  sulphides,  Pembroke  mine. .  22 

10.  Section  along  line  A-A^,  Plate  II 31 

11.  Section  along  line  B-B^  Plate  II 31 

12.  Cross  section  of  the  Sullivan  mine 39 

13.  Sketch  showing  position  of  principal  veins  in  Lubec  lead  mine 44 

14.  Small  vein  in  Lubec  lead  mine 45 

15.  Sketch  showing  position  of  pits  of  Eastern  Exploration  Company  at 

Pembroke ■- 46 

16.  Plan  and  cross  section  of  Robinson  mine,  near  Concord 48 

17.  Vertical  cross  section  of  wall  at  open  cut,  Robinson  mine,  near  Con- 

cord   49 

18.  Plan  of  ore  treatment  at  Milan  mine 51 

19.  Geologic  east- west  cross  section  through  West  Milan,  N.  H.,  north  of 

Milan  copper  mine 54 

20.  Pyrite  cut  by  quartz,  Milan  mine 54 

21.  Section  of  vein  at  east  end  of  115-foot  level,  Milan  mine 55 

22.  Cross  section  of  ore  bodies,  Milan  mine 56 

23.  Plan  of  115-foot  level,  Milan  mine 57 

5 


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in  2010  witii  funding  from 

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SOME  ORE  DEPOSITS  IN  MAINE  AND  THE  MILAN 
MINE,  NEW  HAMPSHIRE. 


By  William  H.  Emmons. 


INTRODUCTION. 

GENERAL   STATEMENT. 


Metal  mining  does  not  rank  as  an  important  industry  in  Maine, 
for,  aside  from  iron  ore,  the  deposits  of  whicli  were  once  worked  with 
some  vigor,  the  metallic  production  of  the  State  has  been  small.  It 
contains,  however,  deposits  of  nearly  all  the  commoner  metals  and, 


Figure  1. — Outline  map  of  southern  Maine. 


owing  to  the  complex  relations  of  the  rocks  and  the  eventful  geologic 
history  of  the  region,  the  number  of  typos  is  not  surpassed  in  many 
areas  of  equal  size  in  regions  of  greater  mineralization  and  larger 
ore  deposits. 


8  SOME    OKE   DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIKE. 

The  economic  reconnaissance  described  in  the  present  paper  was 
made  during  six  weeks  of  the  summer  of  1909,  in  which  time  all  of 
the  most  important  deposits  of  the  metals  other  than  iron  were  visited. 
Figure  1  shows  the  positions  of  the  towns  and  of  villages  near 
which  the  mines  are  located.  As  many  of  them  are  in  localities  where 
the  areal  geology  has  been  worked  out  in  detail  and  where  the  struc- 
tural relations  of  the  rocks  are  well  understood,  the  history  of  the 
ore  deposits  may  be  stated  with  confidence.  The  conditions  for 
underground  work  were  not  good,  because  nearly  all  of  the  mines 
were  closed  down  and  the  shafts  partly  or  entirely  filled  with  water, 
but  owing  to  the  slight  oxidation  of  the  surface,  the  relations  of  the 
deposits  and  the  character  of  the  ores  could  be  studied  in  many  open 
cuts  and  at  the  higher  levels  above  ground  water. 

In  connection  with  this  work  the  Milan  mine,  in  Coos  County,  N.  H., 
was  visited.  The  deposit  which  is  now  successfully  worked  at  this 
mine  is  only  a  few  miles  west  of  the  Maine  boundary  and  closely  re- 
sembles some  of  the  deposits  in  Maine.  Its  description  is  included  in 
this  report  for  the  purpose  of  comparison. 

ACKNOWLEDGMENTS. 

The  writer  gratefully  acknowledges  his  indebtedness  to  George 
Otis  Smith  and  E.  S.  Bastin,  whose  published  papers  have  supplied 
most  of  the  geologic  data  for  this  report  and  who  have  given  the 
writer  unpublished  notes  on  some  of  the  mines;  to  Walclemar  Lind- 
gren,  of  the  United  States  Geological  Survey,  for  direction  and  criti- 
cism ;  to  F.  C.  Robinson,  state  geologist  of  Maine ;  to  Messrs.  J.  B. 
Carper  and  J.  B.  Morris,  of  Portland,  for  many  courtesies;  and  to 
the  owners  of  the  mines  and  prospects,  for  the  free  access  granted  to 
their  properties. 

BIBLIOGRAPHY. 

The  following  list  is  intended  to  include  the  most  important  pub- 
lications on  the  ore  deposits  of  Maine  and  their  associated  rock  forma- 
tions : 

Bartlett,  F.  L.,  Mines  of  Maine,  Portland,  1879. 

A  discussion  of  the  ores,  with  numerous  assays  and  notes  on  the  organ- 
ization and  capitalization  of  various  mining  companies  operating  in  Maine. 
P.A.sriN,  Edson  S.     a  pyrrhotitic  peridotite  from  Knox  County,  Me. — a  sulphide 
ore  of  igneous  origin :  Jour.  Geology,  vol.  16,  1908,  p.  124. 

Describes  a  peridotite  in  which  olivine  and  cupriferous  pyrrhotite  are 
intimately  intergrown  in  such  a  manner  as  to  show  contemporaneous  age. 

Eastport  folio,  (Jeol.  Atlas  TJ.  S.     (In  preparation.) 

Numerous  geologic  data   soon   to  be  published  in  this  folio  have  been 
freely  contributed  by  Mr.  Bastin  and  are  incorporated  in  the  present  report. 
Cakpkr,  J.  B.     The  Milan  mine,  NeAV  Hampshire.     Eng.  and  Min.  .Jour.,  vol.  87, 
1909,  p.  .318. 

A  brief  note  giving  niclal  contents  of  ore  shipments  from  the  Milan  mine. 


IISITRODUCTION.  9 

Hess,  Frank  L.     Some  molybdenite  dejiosits  of  Maine,  TTtah,  and  California  : 
Bull.  U.  S.  Geol.  Survey  No.  340,  1908,  p.  231. 

Describes  tlie  molybdenite  deposits  of  Cooper,  Catherine  Hill,  and  Paris, 
Me.,  and  concludes  tbat  tlie  molybdenite  is  of  pegmatitic  origin. 

Holmes,  Ezekiel,  and  Hitchcock,  C.  H.     Preliminary  report  upon  the  natural 
history  and  geology  of  the  State  of  Maine,  1861. 

This  report  Includes  many  valuable  geological  data,  vsith  notes  on  the 
occurrence  of  bog  iron  ores  and  magnetic  iron  ores  at  various  places. 
Several  occurrences  of  lead  and  zinc  and  other  metals  are  mentioned,  and 
extracts  from  a  report  by  N.  S.  Manross  on  the  Lubec  lead  mine  are 
incorporated. 

Hitchcock,  C.  H.     Geology  of  Maine:  Second  Ann.  Rept.  Natural  History  and 
Geology  of  Maine,  Geology,  1862,  pp.  223-430. 

The  report  includes  detailed  descriirtions  of  rock  formations  and  cross 
sections  showing  the  geologic  structure  at  many  places  along  the  Maine 
coast,  and  gives  some  running  notes  on  the  geology  of  the  northern  portions 
of  the  State.  A  list  of  mineral  occurrences  and  a  catalogue  with  brief 
descriptive  notes  on  Mount  Mica  minerals  is  included.  Incorporated  in  the 
volume  is  a  report  by  G.  L.  Goodale  on  various  occurrences  of  ore  minerals 
and  on  the  economic  possibilities  of  the  iron  ores. 

Jackson,  Charles  T.     First  report  on  the  geology  of  the  State  of  Maine,  1837. 
Some  interesting  notes  of  a   geologic   reconnaissance,   with  descriptions 
of  building  stones  and  various  mineral  occurrences. 

Second  report  on  the  geology  of  the  State  of  Maine,  183S. 

Gives  some  cross  sections  in  the  region  of  Blue  Hill,  with  descriptive  notes 
on   the  rocks   involved.     Describes  granite,   limestone,   and   shale  quarries 
and  the  deposits  of  serpentine  on  Deer  Isle.     Includes  notes  on  the  tech- 
nology of  iron  and  of  copperas  manufacture  on  Jewel  Island,  Casco  Bay. 
Third  annual  report  of  the  geology  of  the  State  of  Maine,  1838. 

Includes  notes  of  geologic  reconnaissance,  with  a  list  of  rocks,  ores,  and 
minerals  from  various  localities. 
Kempton,  C.  W.     Sketch  of  the  new  mining  district  at  Sullivan,  Me. :  Trans. 
Am.  Inst.  Min.  Eng.,  vol.  7,  1878,  p.  349. 

An  account  of  the  geology  and  ore  deposits   at   Sullivan,   with   several 
geologic  cross  sections  of  that  I'egion.     A  paper  of  historical  value,  describ- 
ing deposits  which  have  not  been  worked  for  many  years. 
McCaskey,    H.    D.     Mineral   resources   of   the   United   States   for  1908,   pt.   1, 
Metallic  products,  U.  S.  Geol.  Survey,  1909,  pp.  142,  146,  247,  658. 

Notes  on  various  metalliferous  deposits  of  Maine. 
Smith,  George  Otis.     Quartz  veins  in  Maine  and  Vermont :  Bull.  U.  S.  Geol. 
Survey  No.  225,  1904,  p.  81. 

Describes  quartz  veins  at  Mount  Glines,  Oxford  County,  and  a  pegmatite 
near  Pittston,  Kennebec  County,  which  has  been  erroneously  regarded  as  a 
gold  ore. 

A   molybdenite   deposit   of  eastern   Maine :    Bull.    U.    S.    Geol.    Survey 

No.  260,  1905,  p.  197. 

Graphite  in  Maine :  Bull.  U.  S.  Geol.  Survey  No.  285,  1906,  p.  480. 

Describes  occurrences   of  graphite  near  Madrid,   Franklin   County,   and 

near   Yarmouth,   Cumberland   County. 
Smith,  George  Otis,  Bastin,  Edson  S.,  and  Brown,  Charles  W.     Penobscot 
Bay  folio  (No.  149),  Geol.  Atlas  U.  S.,  U.  S.  Geol.  Survey,  1907. 

This  folio  furnishes  the  most  comprehensive  geologic  data  for  Maine 
now  available,  and  a  considerable  portion  of  the  geologic  descriptions  of 
the  present  report  are  taken  from  it. 


10  SOME    ORE   DEPOSITS   IN    MAINE   AND   NEW    HAMPSHIRE, 

Smith,  George  Otis,  and  David  White.    The  geology  of  the  Perry  Basin :  Prof. 
Paper  U.  S.  Geol.  Survey  No.  35,  1905. 

This  paper  is  the  result  of  an  investigation  of  the  rocks  of  the  Perry 
Basin  to  ascertain  whether  there  is  a  probability  of  finding  coal  there.  The 
rocks  of  this  basin  are  fossiliferous  and  are  interbedded  v\^ith  the  lavas, 
and  their  study  has  resulted  in  disclosing  important  relationships.  The 
spherulitic  rhyolites,  which  are  devitrified  and  somewhat  deformed  by 
metamorphism,  are  interbedded  with  fossiliferous  Silurian  strata  and  are 
believed  to  be  the  effusive  equivalent  of  the  same  magma  which,  solidifying 
at  greater  depth,  formed  the  great  granite  intrusive  that  extends  from 
Robbinston  northward  to  the  vicinity  of  Calais.  The  Perry  formation, 
which  rests  above  the  Silurian  and  is  less  deformed,  is  made  up  of  conglom- 
erate and  sandstone  and  includes  beds  of  basaltic  lavas.  Since  the  Perry 
carries  Devonian  fossils  the  basic  lavas  are  known  to  be  of  that  age. 
Pebbles  of  granite  are  found  in  the  conglomerate  but  not  in  the  underlying 
Silurian  rocks. 

Smock,  John  C.    Mineral  resources  U.  S.  for  1882,  p.  687. 

A  list  of  "  Ores,  minerals,  and  mineral  substances  of  industrial  im- 
portance "  which  are  mined  in  Maine. 

Stone,  George  H.     The  glacial  gravels  of  Maine  and  their  associated  deposits : 
Mon.  U.  S.  Geol.  Survey,  vol.  34,  1899. 

A  comprehensive  report  on  the  glacial  deposits  of  Maine.  A  discussion 
of  glacial  processes  and  a  comparison  of  the  continental  glacier  with  those 
of  the  Rocky  Mountains. 

GEOGRAPHY. 

The  State  of  Maine  is  for  the  most  part  a  low  plateau,  the  higher 
portions  of  which  are  deeply  trenched  by  rivers  and  creeks.  Many 
hills  and  low  mountains  rise  above  this  plateau,  and  it  is  thickly 
dotted  by  lakes  and  ponds.  The  coast  line  is  very  irregular.  Long, 
narrow  bays  with  deep  water  channels  extend  far  inland  and  since 
these  are- navigable  for  small  ocean  craft  transportation  facilities  are 
good  and  freight  rates  low. 

MINIISTG  DEVELOPMENT. 

Granite  and  limestone  are  quarried  in  large  quantities  and  have 
a  wide  market.  The  metalliferous  deposits,  although  they  have  not 
been  abandoned,  are  not  now  being  exploited.  Mining  was  done  in 
a  small  way  in  the  early  part  of  the  nineteenth  century.  In  the 
second  report  by  Charles  T.  Jackson  on  the  geology  of  the  State, 
published  in  1838,  mention  is  made  of  a  pyrite  mine  on  Jewel  Island, 
Casco  Bay,  where  copperas  and  alum  were  manufactured.  Later  the 
iron  ores  of  Mount  Katahdin- were  developed;  and  for  a  long  term 
of  years,  ending  about  1800,  these  deposits  produced  from  2,000  to 
15,000  tons  of  iron  a  year.  The  Lubec  lead  mines,  which  were  dis- 
covered in  the  late  thirties,  were  worked  with  some  vigor  in  the  early 
sixties. 


GEOLOGY.  11 

The  principal  period  of  development  was  from  1878  to  1882, 
during  which  time  the  districts  along  the  coast  were  having  a  mining 
boom  that  in  all  essentials  resembled  those  periods  of  excitement 
notable  in  the  history  of  many  western  camps.  Mining  companies 
with  ample  capitalization  were  organized  to  exploit  the  deposits  of 
Blue  Hill,  Sullivan,  and  near-by  districts.  Substantial  mine  build- 
ings were  erected ;  expensive  machinery  was  installed ;  and  in  some 
instances  mills,  concentrators,  or  smelters  were  built.  At  the  Doug- 
las mine,  in  Blue  Hill,  large  sums  were  spent  on  smelters  and  roasting 
and  leaching  plants  and  several  hundred  tons  of  copper  was  recov- 
ered. In  1883  the  price  of  copper  dropped  considerably  and  the 
Douglas  and  other  mines  of  Blue  Hill  were  closed.  The  silver  mines 
at  Sullivan  were  closed  soon  afterward  and  have  since  been  idle.  The 
mines  at  Lubec  and  the  Robinson  mine,  at  Concord,  have  been  worked 
in  recent  years,  and  between  1900  and  1907  prospecting  was  done  at 
several  places,  but  no  large  operations  have  been  carried  on  since 
the  eighties. 

PRODUCTION  OP  METALS. 

The  quantity  of  metals  produced  in  Maine  can  not  be  given  accu- 
rately. The  total  value  of  all  metals  other  than  iron  is  conservatively 
estimated  at  $400,000,  the  larger  part  of  which  is  copper  from  the 
Blue  Hill  mines.  The  silver  mines  at  Sullivan  and  at  Byard  Point 
probably  yielded  at  least  5,000  ounces.  A  number  of  mines  have 
yielded  relatively  small  quantities  of  lead  and  zinc. 

GEOLOGY. 

The  following  discussion  of  the  general  geology  of  Maine  is  taken 
almost  entirely  from  published  papers  of  G.  O.  Smith  and  E.  S.  Bastin 
(see  pp.  8-9),  and  from  verbal  statements  made  by  them,  and  is 
intended  to  include  only  such  data  as  have  a  direct  bearing  on  the 
genesis  and  history  of  the  ore  bodies. 

SEDIMENTARY  ROCKS. 

Ellsworth  schist  {pre-G ambrianf) . — The  Ellsworth  schist  is  the 
oldest  rock  outcropping  in  the  areas  of  mineralization,  and  is  the 
country  rock  for  many  of  the  ore  deposits.  Large  areas  occur  in 
Hancock  County  near  Blue  Hill  (see  PI.  II),  and  it  extends  eastward 
to  Sullivan  and  beyond.  It  is  composed  of  highly  schistose  meta- 
morphic  rocks  which  presumably  are  the  changed  equivalents  of 
siliceous  shales  and  argillaceous  sandstones.  The  rock  is  purple  to 
greenish  gray  in  color  and  is  finely  foliated.  At  most  places  meta- 
morphism  has  obliterated  all  traces  of  bedding,  but  on  the  east  shore 
of  Skilleys  River  in  the  Mount  Desert  quadrangle  massive  quartz- 
ite  beds  alternate  with  the  more  argillaceous  layers.     Under  the  micro- 


12  SOME    ORE   DEiPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 

scope  the  chief  constituent  minerals  are  seen  to  be  quartz  and  chlorite. 
The  chlorite  occurs  in  thin  parallel  plates  and  gives  the  rock  its 
schistosity.  The  quartz  fragments  have  been  rotated  during  the 
process  of  metamorphism  so  that  the  longer  axes  lie  parallel  to  the 
chlorite  leaves.  Some  biotite,  muscovite,  epidote,  and  magnetite  are 
present  in  varying  quantities.  The  schist  is  intruded  by  the  Castine 
volcanic  rock,  by  granite,  and  by  diorite  and  is  clearly  older  than  all 
of  these.  Since  formations  known  to  be  later  than  the  Ellsworth  are 
very  probably  Cambrian,  the  Ellsworth  is  presumably  very  early 
Cambrian  or  pre-Cambrian. 

Isleshoro  formation  {^Cambrian?). — Thelslesboro  formation,  which 
occupies  a  large  part  of  Islesboro,  is  a  series  of  metamorphosed  slates 
and  limestones  at  least  300  feet  thick.  It  is  everywhere  strongly 
folded  and  at  many  places  shows  a  well-developed  slaty  cleavage 
which  intersects  the  bedding  planes  at  high  angles.  On  Seven  Hun- 
dred Acre  Island  the  slaty  members  contain  intensely  crumpled 
quartz  veins.  The  Coombs  limestone  member  forms  the  top  of  the 
formation  and  is  overlain  by  the  Battie  quartzite.  In  the  southern 
part  of  Job  Island  the  limestone  is  interbedded  ^vith  dark-green 
layers  which  seem  to  be  volcanic  tuffs  or  muds  of  the  North  Haven 
greenstone.  The  slate  member  likewise  contains  volcanic  material  of 
the  same  age  and  origin.  In  the  metamorphism  which  has  affected  the 
formation  the  limestone  has  completely  recrystallized  and  the  shaly 
beds  have  at  most  places  become  schists.  No  fossils  have  been  found 
in  the  formation,  but  on  stratigraphic  grounds  it  is  thought  to  be  of 
Cambrian  age. 

Battle  quartzite  {Cambrian f) .—The  Battie  quartzite,  which  con- 
sists of  massive  buff  quartzite  and  quartzite  conglomerate  several 
hundred  feet  thick,  rests  directly  upon  the  Coombs  limestone  member 
of  the  Islesboro  formation  without  any  apparent  unconformity.  It  is 
well  exposed  at  Mount  Battie,  a  small  mountain  near  Camden.  It 
is  not  highly  crumpled,  as  is  the  slate  phase  of  the  Islesboro,  because 
it  was  less  yielding.     It  is  believed  to  be  of  Cambrian  age. 

Penobscot  formation  {Cambrian f). — The  Penobscot  formation, 
typically  developed  along  the  west  shore  of  Penobscot  Bay,  is  com- 
posed of  metamorphosed  shaly  sediments  which  overlie  the  Battie 
quartzite.  A  distinct  and  perfect  schistosity  is  commonly  j^resent, 
and  the  formation  is  at  places  intensely  folded  into  isoclinals.  At 
Ducktrap  Harbor  the  slates  are  intruded  by  granite,  and  garnet,  anda- 
lusite,  and  other  minerals  have  formed  by  contact  metamorphic  proc- 
esses.   The  Penobscot  formation  is  believed  to  be  of  Cambrian  age. 

Am,es  Knob  formation  {Silurian). — The  Ames  Knob  formation, 
which  is  made  up  of  limestones,  red  shales,  and  conglomerate,  con- 
tains Niagara  fossils.  It  has  been  gently  tilted  in  places,  but  the 
compressed  folds  and  minor  crumplings  characteristic  of  the  Penob- 


GEOLOGY.  13 

scot,  Islesboro,  Castine,  and  North  Haven  formations  are  entirely 
absent.  Clearly  it  has  been  deposited  since  the  time  of  the  regional 
metamorphism  of  the  country.  The  basal  member  is  a  conglomerate, 
which  includes  rounded  fragments  of  North  Haven  greenstone  and 
of  green  slate,  quartzite,  and  vein  quartz.  The  upper  portion  of  the 
formation  contains  volcanic  material,  and  in  the  Penobscot  Bay  quad- 
rangle it  grades  into  the  Thorofare  andesite.  In  the  Perry  Basin 
fossiliferous  Silurian  strata  are  interbedded  with  rhyolites. 

Perry  formation  {Devonian). — The  Perry  formation,"  which  in  the 
Perry  Basin  overlies  the  Silurian  rocks,  consists  of  a  lower  conglom- 
erate member,  above  which  are  beds  of  basaltic  lava  and  breccia. 
Above  the  latter  is  coarse  red  and  brown  sandstone  with  included 
conglomerate  and  lava  layers.  Above  this  still  is  a  green  amygdaloid 
and  sandstone.  The  plant  remains  show  the  formation  to  be  of 
Devonian  age.  Except  for  certain  glacial  deposits,  formed  in  com- 
paratively recent  times  by  the  ice  sheet  which  covered  the  entire  State, 
no  sedimentary  beds  younger  than  the  Perry  are  known  to  occur  in 
the  areas  of  mineralization. 

IGNEOUS  ROCKS. 

Castine  formation  {Camhrianf). — The  Castine  formation,  which 
is  typically  developed  on  the  Castine  Peninsula,  is  made  up  of  light- 
colored  lavas  and  pyroclastic  rocks  including  rhyolite,  dacite,  and 
andesite.  These  rocks  occur  as  flow  breccias,  conglomerates,  tuffs, 
intrusive  sheets,  and  dikes.  The  great  bulk  of  them  are  meta- 
morphosed dynamically,  and  some,  which  were  presumably  volcanic 
muds,  are  highly  schistose.  Some  of  the  tuffs  seem  to  have  been  rich 
in  lime  carbonate.  Chlorite,  sericite,  biotite,  and  cordierite  have  in 
places  been  developed  in  the  Castine  by  secondary  processes.  Tremo- 
lite,  biotite,  and  other  minerals  have  developed  by  contact  meta- 
morphism. A  similar  association  of  minerals  with  sulphides  and 
abundant  garnet  is  found  at  the  Deer  Isle  mine.  (See  p.  37.)  The 
Castine  formation  is  in  a  general  way  contemporaneous  with  the 
Islesboro  formation  and  is  believed  to  be  of  Cambrian  age. 

North  Haven  greenstone  {Cambrian  ?). — The  North  Haven  green- 
stone, which  is  extensively  developed  on  the  island  of  North  Haven 
and  on  neighboring  smaller  islands,  is  made  up  of  regionally  meta- 
morphosed diabase,  basic  trachyte,  and  albite-augite  syenite,  which 
occur  as  tuffs,  flows,  dikes,  and  sills.  The  different  varieties,  whicli 
are  at  many  places  indistinguishable,  are  associated  in  the  most  inti- 
mate and  irregular  manner  and  are  believed  to  be  contemporaneous. 
At  some  places  these  rocks  show  highly  developed  schistosity. 
Fibrous  actinolite,  zoisite,  calcite,  muscovite,  biotite,  and  chloritic 


»  Smith,  G.  0.,  and  White,  David,  Prof.  Paper  U.  S.  Geol.  Survey  No.  35,  1905,  p.  28. 


14  SOME    ORE   DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 

minerals  are  developed  by  regional  metamorphism.  The  North 
Haven  greenstone  is  older  than  the  Silurian  sediments;  and  since 
the  Islesboro  formation  contains  much  fragmental  material  of  com- 
mon age  and  origin  with  the  North  Haven  greenstone,  the  latter  is 
believed  to  be  contemporaneous  with  the  Islesboro  and  nearly  con- 
temporaneous with  the  Castine.  Both  formations  are  probably 
Cambrian. 

Thorofare  andesite  {Silurian). — The  Thorofare  andesite,  which  is 
extensively  developed  along  the  Fox  Island  Thorofare,  includes 
massive  porphyritic  andesite,  amygdaloid,  tuffs,  flow  breccias,  and 
conglomerate.  These  volcanic  rocks,  which  are  not  regionally  meta- 
morphosed, overlie  the  upper  members  of  the  Ames  Knob  (Silurian) 
formation  and  have  about  the  same  attitude.  The  red  shales  at  the 
top  of  the  Ames  Knob  contain  volcanic  dust,  which  probably  repre- 
sents the  earliest  Thorofare  eruptions. 

Vinalhaven  rhyolite  {Silurian). — The  Vinalhaven  rhyolite,  ex- 
posed in  the  northwestern  part  of  the  island  of  Vinalhaven,  is  made 
up  of  surface  flows.  Some  are  glassy  and  show  flow  structure ;  some 
are  taxitic  and  spherulitic.  They  overlie  the  Thorofare  andesite, 
and  at  some  places  fragments  of  the  latter  are  mixed  with  the  rhyolite 
flows,  the  rhyolite  constituting  the  matrix.  They  are  in  the  main 
younger  than  the  Thorofare,  but  near  the  line  of  contact  of  the  two 
formations  beds  of  rhyolite  alternate  with  beds  of  andesite.  It 
seems  probable  that  the  two  kinds  of  lavas  were  erupted  from  sepa- 
rate neighboring  vents,  the  volcanic  activity  beginning  with  the 
eruption  of  the  andesite  and  ending  with  that  of  the  rhyolite.  The 
andesites  and  rhyolites  are  of  post-Niagara  age,  probably  late  Silu- 
rian, and  older  than  the  granite. 

Granite. — Along  the  Maine  coast  from  Calais  to  Portland  and 
beyond  granite  covers  large  areas.  At  most  places  it  is  gray  or  pink 
and  medium  grained.  The  common  constituents  are  orthoclase, 
microcline,  albite,  biotite,  and  muscovite.  The  granite  shows  no 
schistosity  such  as  results  from  regional  metamorphism.  It  cuts  the 
Ellsworth,  the  Castine,  and  other  pre-Silurian  formations  and  sends 
off  apophyses  into  them.  The  intruded  rock  is  frequently  recrystal- 
lized  near  the  contact,  where  some  andalusite  has  formed,  but  no  ex- 
tensive garnet  zones  are  developed.  The  granite  cuts  rocks  which  are 
known  to  be  younger  than  the  Ames  Knob  formation,  and  it  is  there- 
fore as  late  as  Silurian.  In  the  Perry  Basin  no  granite  pebbles  are 
found  in  the  Silurian,  but  late  Devonian  conglomerates  (Perry)  con- 
tain abundant  rounded  fragments  of  the  granite.  The  coast  granites 
of  Maine  were  therefore  intruded  in  late  Silurian  or  early  Devonian 
time,  and  it  has  been  suggested  "  that  they  are  about  contemporaneous 

»  Smith,  G.  O.,  Prof.  Paper  U.   S.  Geol.   Survey  No.   35,   1905,  p.  20. 


GEOLOGY.  15 

Avitli  certain  of  the  Silurian  rhyolites.  The  granite  apparently  was 
not  rich  in  metals,  although  some  of  the  ore  deposits  appear  to  be 
related  to  it  genetically. 

Diorite^  etc. — Diorite,  diabase,  and  gabbro  are  associated  with  the 
granite  and  are  believed  to  be  somewhat  earlier  but  essentially  con- 
temporaneous differentiations  from  the  same  magma.  They  are  dark 
rocks  of  medium  grain  and  are  free  from  schistosity.  At  some 
places  diorite  and  granite  may  be  seen  grading  one  into  the  other, 
and  dikes  of  either  rock  may  cut  the  other.  The  Gouldsborough 
lode  is  a  fissure  vein  in  diorite  which  near  by  is  brecciated  and 
cemented  by  medium-grained  granite. 

Basic  lava  flows. — In  the  Perry  Basin,  near  Lubec,  in  Pembroke, 
and  at  many  other  places  in  Washington  County  there  are  great 
flows  of  basic  lavas,  including  basalts,  diabase,  and  "  trap  rock." 
In  the  Perry  Basin  these  are  interbedded  with  sandstone  and  con- 
glomerate carrying  late  Devonian  fossils,  showing  that  at  least  some 
of  the  flows  are  of  late  Devonian  age. 

Basic  dikes. — The  granite  and  the  older  rocks  are  cut  by  dikes  of 
diabase,  basalt,  and  analcite  basalt.  Some  of  these  are  doubtless 
very  old,  others  are  believed  to  be  the  intrusive  equivalents  of  the 
lavas  included  in  the  Perry  formation,  while  others  still  are  probably 
Mesozoic  (Triassic?).  A  basaltic  dike  cuts  across  the  Robinson  lode 
at  Concord,  Somerset  County,  and  is  very  clearly  later  than  the  ore. 
The  basalt  at  the  intersection  is  so  fresh  that  even  the  olivines  shoAv 
very  little  of  the  characteristic  alteration  to  serpentine  along  cracks. 

ORE  DEPOSITS. 

CLASSIFICATION  OF  DEPOSITS. 

The  principal  ore  deposits  of  Maine,  not  including  the  iron  ores 
nor  the  gem-bearing  pegmatites,  may  be  divided  into  three  groups — 
(1)  deposits  formed  before  the  end  of  the  last  period  of  great 
regional  metamorphism ;  (2)  deposits  associated  with  the  granite  in- 
trusions; and  (3)  deposits  associated  with  eruptions  of  diabase  or 
trap. 

DEPOSITS   OLDER   THAN    REGIONAL.    METAMORPHISM. 

Distribution  and  character. — The  pre-metamorphic  deposits  are  the 
most  important.  All  the  known  representatives  are  in  Hancock 
County,  in  the  hilly  country  between  Penobscot  and  Blue  Hill  bays. 
They  include,  stated  in  order  of  importance,  pyritic  copper  ores, 
garnetiferous  zinc  ores,  and  siliceous  zinc-lead-silver  ores.  All  are 
in  the  Ellsworth  schist  and  the  Castine  volcanic  rocks — the  Twin  Lead, 
Douglas,  Blue  Hill,  Stewart,  Mammoth,  Owen  Copper,  Granger,  and 
Weil  Freddie  being  in  the  Ellsworth,  and  the  Tapley,  Deer  Isle, 


16 


SOME    ORE   DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 


Cape  Rozier,  Emerson,  and  Hercules  in  the  Castine.  In  all  the  mines 
in  which  the  ore  bodies  are  exposed  the  sulphides  appear  disseminated 
through  the  rock,  as  lenses  approximately  parallel  to  the  schistosity, 
or  as  deformed  breccia  zones. 

The  copper  deposits  near  Blue  Hill  and  Brooksville  are  the  most 
important.  All  of  the  mines  have  lain  idle  for  years  and  their 
underground  workings  are  inaccessible,  but  the  character  of  the  ore 
and  its  relations  to  the  structure  are  shown  in  a  number  of  deep 
open  cuts.  Except  at  the  Tapley  mine,  which  is  in  the  Castine  forma- 
tion, the  Blue  Hill  and  Brooksville  deposits  are  all  in  the  Ellsworth 
schist.  This  is  a  siliceous  sedimentary  rock  which  has  been  meta- 
morphosed at  great  depths  and  under  pressure.  (See  p.  11.)  The 
minerals  of  the  ore  are  quartz,  chlorite,  muscovite,  biotite,  pyrite, 
chalcopyrite,  pyrrhotite,  magnetite,  arsenopyrite,  bornite,  chalcocite, 
and  a  little  zinc  blende  and  galena.  Near  Blue  Hill  the  deposits 
lie  approximately  parallel  to  the  schistosity,  striking  from  S.  87°  E. 

to   N.    77°    E.    and    dipping 

from  45°  S.  to  vertical. 

The  lodes  are  from  5  to  20 
feet  wide  and  are  said  to  per- 
sist along  the  strike  for  sev- 
eral hundred  feet.  Their 
central  portions  are  as  a  rule 
composed  of  massive  pyrite, 
with  which  some  chalcopyrite 
and  other  sulphides  are  inter- 
grown.  Some  quartz  is  pres- 
ent. Toward  the  wall  thin 
slabs  of  schistose  quartz  and 
chloritic  rock  are  included 
in  the  pyritic  ore.  These  slabs  and  their  constituent  minerals  lie 
nearly  parallel  to  the  schistosity  of  the  country  rock  and  the  trend  of 
the  deposit.  The  walls  themselves,  which  are  of  the  same  composition 
as  the  slabs,  contain  stringers  of  pyrite.  Thus  there  is  a  gradation 
from  the  center  of  the  deposit,  which  is  in  the  main  massive  pyrite, 
to  the  country  rock,  which  carries  only  a  little  pyrite.  Comb  struc- 
ture and  druses  with  crustified  banding  are  lacking.  At  some  places, 
notably  in  the  Twin  Lead  and  Tapley  mines,  small  veins  of  the 
sulphides  are  crumpled  parallel  to  the  crumpling  of  the  schist,  as 
illustrated  by  figures  2  and  3. 

In  the  Mikn  mine,  New  Hampshire  (see  p.  50),  deposits  of  the  same 
general  character  occur  in  tAvo  overlapping  lenses.  These  two  lenses 
arc  clearly  parts  of  a  single  ore  body  which  was  torn  apart  during 
the  process  of  regional  metamorphism.  At  that  time  the  country 
rock  was  deformed  by  fiowage  and  the  pyritic  deposit  by  fracture; 


FiGURK  2. — Stringer  of  contorted  pjTite  in  con- 
torted rhyolite  near  the  Tapley  lode. 


CLASSIFICATION    OF   DEPOSITS. 


17 


that  is,  the  depth  was  such  that  the  jDressure  due  to  the  weight  of  the 
overlying  rocks  exceeded  the  crushing  strength  of  the  quartz-chlorite 
schist  and  was  inferior  to  that  of  the  pyrite  and  quartz.  The  schistos- 
ity  of  the  country  rock  near  by  is  parallel  to  the  line  of  separation, 


I  Foot 

J 


FIGURE  3. — Quartz-pyrite  veinlet  leading  off  from  Twin  Lead  lode.     The  crumpling  of  the 
•  pyrite  shows  that  it  is  older  than  the  metamorphism  of  the  inclosing  Ellsworth  schist. 

which  wraps  around  the  broken  ends  of  the  ore  body.  The  fault,  if 
it  be  so  called,  is  reverse.  The  place  of  separation  is' a  highly  sili- 
ceous portion  of  the  lode  and  one  where  the  ore  is  highly  crumpled. 
Perhaps  future  exploration  will  show  that  some  of  the  lodes  at  Blue 
Hill  which  are  said  to  be  overlapping  in  the  underground  workings 


40  Feet 


E^GCRE  4. — Plan  of  part  of  the  115-foot  level,  Milan  mine,  New  Hampshire. 

are  joined  at  their  ends  by  thin  fissures  and  that  the  schistosity  of  the 
country  rock  along  such  fissures  is  parallel  to  them,  as  indicated  in 
figure  4. 

The  wall  rock  does  not  show  leaching  or  changes  like  those  com- 
monly resulting  fromhot-water  action  of  vein-forming  solutions,  and 
42381°— Bull.  432—10 2 


18 


SOME    ORE    DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 


if  ever  changed  by  the  processes  of  hydrothermal  metamorphism,  the 
changes  have  been  obscured  by  later  regional  metamorphism.  The 
latter  process  must  also  have  destroyed  such  features  as  druses  with 
crustified  banding  and  comb  structures,  if  they  were  ever  present. 

MetamorphisTn. — The  behavior  of  the  sulphides  during  regional 
metamorphism  is  noteworthy.  Where  the  ore  is  nearly  pure  sulphide, 
composed  of  pyrite  with  some  chalcopyrite,  it  is  crushed  and  rece- 
mented  by  pj^rite  or  by  chalcopyrite.  It  then  appears  massive  and 
shows  little  or  no  schistosity,  and  one  examining  the  central  part  of 
the  lode  only  Avould  not  suppose  that  it  had  been  deformed  with  the 
metamorphism  of  the  schists.  But  near  the  walls,  in  the  lower-grade 
ore  composed  of  pyrite,  quartz,  chlorite,  and  mica,  there  is  a  well- 
defined  schistosity,  as  shown  in  figure  6.  From  microscopic  studies  it 
is  seen  that  some  of  the  crushed  fragments  of  pyrite  have  oriented 


Figure  5. — Ore  from  Twin  Lead  mine,  Blue  Hill,  Maine.  The  schistosity  was  developed 
after  the  ore  was  formed,  a,  Quartz;  6,  pyrite;  c,  chlorite  schist.  (Compare  fig.  8, 
p.  21.) 

themselves  parallel  to  the  schistosity  between  the  grains  of  quartz 
and  chlorite.  The  crushing  is  especially  well  shown  where  two 
crystals  of  pyrite  are  pressed  against  each  other  or  against  a  grain 
of  quartz.  If  the  pyrite  crystals  are  surrounded  by  chlorite  or  by 
mica,  they  are  j)rotected  by  these  yielding  minerals,  but  where  two 
pyrite  crystals  touch  they  are  shattered  and  recemented.  This  fea- 
ture is  illustrated  by  figure  6,  which  shows  crystals  of  pyrite  that 
appear  in  hand  specimens  to  be  quite  homogeneous.  Some  perfect 
crystals  of  pyrite  are  formed,  however,  from  iron  sulphide  dissolved 
and  rejorecipitated ;  such  are  found  mainly  in  thin  crumpled  seams 
where  movement  has  been  most  intense.  Under  these  conditions 
cubes  and  octahedra  are  developed  rather  than  pyritohedra  or  pen- 
tagonal dodecahedra.  The  pyrite  was  deposited  in  perfect  crystals 
even  under  the  conditions  of  great  pressure  and  the  jDresence  of  other 


CLASSIFICATION    OF    DEPOSITS. 


19 


minerals.  The  great  crystallizing  power  of  pyrite  is  well  known. 
It  is  so  great  that  when  pyrite  replaces  other  minerals  exactly  enough 
of  their  substance  is  dissolved  to  make  a  space  for  the  pyrite.  As  an 
example  may  be  cited  the  common  case  of  quartzites  in  which  two  or 
more  of  the  rounded  grains  of  qaartz  are  half  dissolved  and  one  per- 
fect pyrite  crystal  fills  completely  the  space  left  where  the  parts  of 
quartz  grains  were  removed. 

It  is  no  easy  task  to  determine  the  character  of  these  deposits 
before  they  were  metamorphosed,  but  this  may  be  inferred  from 
their  present  condition  and  mineralogical  character.  The  diagnostic 
value  of  the  minerals  is  lessened  by  the  fact  that  nearly  all  of  them 
may  be  produced  under  conditions  of  regional  metamorphism  wher- 
ever the  necessary  ele- 
ments are  at  hand. 
Before  metamorphism 
the  pyritic  copper  de- 
posits of  Blue  Hill  and 
Brooksville  were  pre- 
sumably fissure  veins 
of  replacement  tyipes 
and  disseminated  ores 
along  fractured  zones. 
At  the  zinc  mine  at 
Deer  Isle  (see  p.  37) 
garnet,  actinolite,  and 
calcite  are  abundant 
and  are  all  micro- 
scopically banded  par- 
allel to  the  schistosity 
of  the  country  rock 
and  to  the  tablets  of 
massive  sulphides. 
This  deposit  is  be- 
lieved to  be  a  contact-metamorphic  deposit  which  has  been  regionally 
metamorphosed.  An  alternate  hypothesis  is  that  the  garnet  and 
tremolite  were  developed  by  processes  of  regional  metamorphism 
when  the  ore  body  was  subject  to  the  stresses  which  developed  its 
schistosity.  The  garnet,  however,  is  not  in  the  perfect  crystals  which 
usually  form  under  such  conditions,  but  occurs  in  crumpled  bands, 
mashed  and  very  highly  fractured,  alternating  with  the  other  min- 
erals. (See  fig.  7  and  PL  I,  A.)  Further,  garnet  and  actinolite  are 
rare  or  absent  in  the  Blue  Hill  copper  deposits,  which,  with  respect 
to  regional  metamorphism,  have  had  a  similar  histor3^  The  silver 
deposits  of  the  Cape  Rozier,  Hercules,  and  Emerson  mines,  which 
from  the  character  of  the  ore  are  believed  to  belong  to  this  very 


ildiam. 


Figure  6. — Thin  section  of  ore  from  Milan  mine,  New 
Hampsliire.  Tlie  pyrite  has  been  shattered  and  re- 
cemented,  p,  Pyrite ;  cp,  chalcopyrite ;  c,  chlorite ; 
q,  quartz. 


20 


SOME    OEE   DEPOSITS   IN    MAINE    AND    NEW    HAMPSHIRE. 


old  group,  are  not  well  exposed  and  their  primary  origin  is  not 
understood. 

Origin. — The  source  of  the  solutions  which  deposited  the  primary 
ores  is  not  known.  The  youngest  rocks  of  this  area  which  contain 
the  schistose  ores  are  the  greatly  metamorphosed  Castine  intrusives 
and  flows.  All  of  these  ores  may  have  been  formed  during  or  at  the 
close  of  the  volcanic  period  of  the  Castine  and  North  Haven  erup- 
tives,  and  they  may  have  been  formed  by  solutions  contributed  by 
intrusive  rocks  such  as  the  North  Haven  greenstone  and  the  andesites 
associated  with  the  Castine  formation.  The  North  Haven,  which 
includes  diabase,  basic  trachyte,  and  albite-augite  syenite,  occurs  at 

some    places    as    dikes 
^  ^  *  -     and    sills    of    approxi- 

mately the  same  age  as 
the  Castine.^  If  the 
garnetiferous  zinc  ores 
of  Deer  Isle,  which 
seem  to  have  been  de- 
posited in  calcareous 
tuffs  of  the  Castine  for- 
mation, are  contact- 
metamorphic  deposits 
formed  near  the  mar- 
gin of  a  North  Haven 
greenstone  intrusive, 
then  the  thickness  of  the  Castine  above  the  tuffs  must  have  been 
considerable,  for  such  deposits  are  not  formed  at  shallow  depths. 


b  b 

Figure  7. — Thin  section  of  schistose  ore  from  Deer  Isle 
mine,  showing  parallel  bands  of  garnet,  sericite,  and 
sulphides,  a.  Chlorite  and  sericite  ;  h,  fractured  gar- 
net ;  c,  pj'rite,  blende,  and  galena. 


DEPOSITS    ASSOCIATED    WITH    GRANITE    INTRUSIONS. 

The  deposits  associated  with  granite  intrusions  include  the  Sullivan, 
Gouldsborough,  and  West  Franklin  mines,  the  Owen  lead  deposit  at 
Blue  Hill,  and  the  molybdenum  mine  at  Catherine  Hill.  The  deposits 
are  (1)  fissure  veins  in  schist  and  diorite  near  intrusive  granite; 
(2)  molybdenum  sulphide  ore  associated  with  the  pegmatitic  phases 
of  the  granite  magma;  and  (3)  lead  sulphide  consolidated  with  the 
rock-making  minerals  of  the  granite. 

Fissure  veins. — The  chief  metals  of  the  fissure  veins  are  silver  and 
zinc.  The  principal  minerals  are  quartz,  zinc  blende,  galena,  pyrite, 
chalcopyrite,  and  arsenopyrite,  but  at  the  Sullivan  mines  stephanite, 
argentite,  native  silver,  and  tetrahedrite  are  reported  to  be  present. 
Pyrrhotite  is  lacking.  In  composition  and  structural  features  these 
lodes  contrast  strongly  with  the  regionally  metamorphosed  deposits. 


"Smith,  G.  O.,  Bastin,  E.  S.,  and  Brown,  C.  W.,  Penobscot  Bay  folio   (No.  149),  Geol. 
Atlas  U.  S.,  U.  S.  Geol.  Survey,  1907,  p.  7. 


U.    S.    GEOLOGICAL    SURVEY 


BULLETIN    432       PLATE    I 


A.     PHOTOMICROGRAPH  OF  SCHISTOSE  ORE  FROM  DEER  ISLE  MINE. 


B.     PHOTOMICROGRAPH   OF  THIN   SECTION   OF  ORE  FROM  OWEN   LEAD   PROSPECT. 


MINERALOGY. 


21 


Although  some  of  them  are  in  the  quartz-chlorite  (Ellsworth)  schist 
they  cut  across  the  schistosity  of  that  rock  and  include  angular  frag- 
ments of  it.  These  fragments  are  slightly  rounded  by  the  vein- 
forming  solutions  and  are  arranged  haphazard  with  respect  to 
schistosity.  Drusy  cavities  with  crustified  banding  and  comb  struc- 
ture are  common.  These  features  are  illustrated  by  figure  8,  which 
is  a  sketch  of  the  ore  at  Sullivan.  Comparison  of  this  ore  with  the 
schistose  Twin  Lead  ore  illustrated  by  figure  5  shows  many  of  the 
points  of  difference  between  deposits  associated  with  granite  intru- 
sions and  those  of  earlier  origin. 

The  Gouldsborough  mine  is  in  quartz  diorite,  a  rock  which  shows 
no  regional  metamorphism  and  is  believed  to  be  an  earlier  differentia- 
tion from  the  granite  magma.  Its  age  relations  with  the  granite  are 
shown  near  the  mine,  where  broken  pieces  of  the  diorite  are  cemented 
by  granite.     The  lode  is  a  fissure  vein  or  sheeted  zone  composed 


Figure  8. — Ore  from  Sullivan  mine      The  schistosity  was  developed  before  the  ore  was 
formed,     a,  Fragments  of  schist;  b,  vein  quartz.      (Compare  fig.  5,  p.  18.) 

of  banded  sulphides  and  quartz.  Near  the  lode  the  hot  solutions  have 
changed  the  country  rock,  and  much  chlorite,  some  pyrite,  epidote, 
and  sericite  have  replaced  the  minerals  of  the  quartz  diorite. 

The  zinc  mine  at  Concord,  near  Bingham,  Somerset  County,  is  a 
siliceous  deposit  occupying  the  crest  of  an  anticlinal  axis.  The  ore 
is  not  metamorphosed  and  may  belong  to  the  granite  period  of  miner- 
alization, but  the  deposit  is  isolated  and  the  geology  of  the  surround- 
ing area  has  not  been  studied  with  sufficient  care  to  justify  an  attempt 
to  classify  it. 

Molybdenite  and  lead  deposits. — The  Catherine  Hill  molybdenite 
deposit  (PL  III,  B)  and  the  Owen  lend  deposit  (PI.  I,  B)  are  mag- 
matic  segregations  which  belong  to  this  period  of  mineralization.  The 
galena  and  the  molybdenite  inclose  well-shaped  crystals  of  feldspar 
rounded  on  the  edges,  but  clearly  idiomorphic,  or  nearly  so.  The 
sulphides  solidified  at  the  time  the  rock  was  formed.     A  similar 


22 


SOME    OEE   DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 


crystallization  of  pyrrhotite  in  peridotite  from  Knox  County  has 
been  described  by  E.  S.  Bastin.'^ 

DEPOSITS   ASSOCIATED   WITH   DIABASE   AND   TRAP. 

The  deposits  associated  with  the  diabase  and  trap  include  those  of 
the  Lubec  lead  mine,  the  Denbow  Point  mine,  and  the  copper  and 
zinc  prospects  in  Pembroke,  all  of  which  are  in  Washington  County 
and  in  the  Eastport  quadrangle.  The  country  rock  is  at  no  place 
greatly  metamorphosed  by  pressure  and  the  ores  show  no'  schistosity. 
The  galena-blende  ores  at  Lubec  are  deposited  in  thin  fissures  and  in 
brecciated  zones.  The  ores  at  Pembroke  are  deposited  in  vesicular 
cavities  and  in  nonpersistent  fractures  in  basic  flows,  as  illustrated  by 
figure  9. 

The  deposits  of  this  group  show  drusy  cavities  and  crustified  band- 
ing.   The  minerals  of  the  ore  are  quartz,  dolomite,  calcite,  galena,  zinc 

blende,   pyrite,    chalcopyrite, 
a.         a,      cc    CL  a.  cl  bornite,     and     arsenopyrite. 

The  oxidized  ore  is  composed 
of  quartz,  limonite,  and  a 
little  manganese  oxide  and 
copper  carbonate.  The  Lu- 
bec ores  carry  some  silver. 
No  pyrrhotite  is  present  in 
the  ores  of  these  deposits  and 
no  massive  magnetite,  al- 
though the  crushed  ore  yields 
a  trace  of  magnetic  dust — 
possibly  an  oxidation  prod- 
uct. As  a  result  of  the  reactions  of  the  vein-forming  solutions  with 
the  wall  rock  much  secondary  chlorite  and  calcite  were  formed  but 
only  a  little  sericite. 

MINERALOGY. 

The  following  list  includes  the  most  important  minerals  of  the 
deposits,  with  brief  descriptive  notes  of  their  occurrence.  Only  the 
most  important  of  the  rock-making  minerals  are  mentioned  and  no 
attempt  is  made  to  list  the  minerals  of  the  pegmatites,  except  those 
which  are  closely  related  in  genesis  to  some  of  the  ore  deposits.  The 
pegmatites  of  Maine  are  to  be  treated  in  a  forthcoming  paper  by 
E.  S.  Bastin. 

ActinoUte. — Developecl  by  secondary  processes  in  some  of  the  regionally 
metamorphosed  schists  and  intimately  associated  with  the  garnetiferous  ores  at 
the  Deer  Isle  mine. 


Figure  9. — Brecciated  diabase  cut  by  quartz  and 
sulphides,  Pembroke  mine,  a,  Quartz  and  ore  ; 
by  diabase. 


"  Pyrrhotitic  peridotite  from  Knox  County,  Maine — a  sulphide  ore  of  igneous  origin  ; 
Jour.  Geology,  vol.  IG,  1908,  p.  124. 


MINERALOGY.  23 

AlMte. — A  common  constituent  of  the  granite  and  some  other  igneous  roclvS. 
Appears  as  idiomorphic  crystals  surrounded  by  galena  at  the  Owen  lead  mine 
and  as  crystals  surrounded  by  molybdenite  at  the  Catherine  Hill  molybdenite 
mine. 

Apatite. — ^A  common  accessory  constituent  of  the  granite  and  other  igneous 
rocks.     Crystals  of  apatite  are  surrounded  by  galena  in  tlie  Owen  lead  prospect. 

Argentite. — Reported  from  the  silver  mines  at  Sullivan. 

Arsenopyntc. — Present  in  the  copper  mines  at  Blue  Hill  and  in  the  silver 
mines  at  Sullivan,  but  not  abundant  at  either  place. 

Augitc. — Abundant  in  the  basic  igneous  rocks,  but  not  noted  in  connection 
with  any  of  the  ore  deposits. 

Barite. — Not  abundant.  A  little  was  noted  on  the  dump  at  the  Deer  Isle  mine 
and  at  the  Sullivan  mine. 

Biotite. — ^A  common  constituent  of  the  schist.  Is  present  in  the  schistose 
copper  ores. 

Bornite. — Not  abundant  in  any  of  the  deposits  but  appears  in  some  of  those 
at  Blue  Hill,  at  the  Lubec  lead  mine,  and  at  the  prospects  in  Pembroke. 

Calcitc. — Rare  or  absent  in  the  schistose  ores  at  Blue  Hill  but  present  in  the 
Deer  Isle  zinc  ore,  in  the  Lubec  lead  ores,  and  in  the  wall  rock  near  the  lodes 
along  some  of  the  fissure  veins. 

Cerargyrite. — Reported  from  the  silver  mines  at  Sullivan. 

Chalcocitc. — Not  abundant  in  any  of  the  deposits.  Sparingly  present  as 
dark  films  on  chalcopyrite  at  the  copper  mines  near  Blue  Hill. 

Clialcopyrite. — Present  in  nearly  all  of  the  deposits.  An  important  ore  min- 
eral in  the  schistose  copper  ores  of  Blue  Hill. 

Chlorite. — Abundantly  developed  in  the  schist  and  intimately  associated  with 
the  schistose  ores ;  also  the  most  abundant  mineral  formed  by  metasomatic 
processes  along  the  fissure  veins  in  igneous  rocks. 

Copper,  native.— An  oxidation  product  of  the  copper-bearing  sulphides.  Re- 
ported from  the  Douglas  mine  and  the  Owen  mine  at  Blue  Hill. 

Cuprite. — Sparingly  present  in  the  zone  of  oxidation  of  the  copper  deposits. 

Epidote. — Appears  with  quartz  in  some  small  veinlets  in  Pembroke.  Devel- 
oped with  chlorite  and  sericite  in  the  quartz  diorite  wall  rock  of  the  Goulds- 
borough  lode. 

Galenn. — Sparingly  present  in  nearly  all  of  the  deposits.  More  abundant  at 
the  Lubec  and  the  Bingham  mines.  Intergrown  with  feldspar  at  the  Owen  lead 
prospect. 

Garnet. — Abundantly  present  in  the  schistose  ores  of  the  Deer  Isle  mine, 
where  it  has  been  regionally  metamorphosed.  Sparingly  developed  in  intruded 
rocks  near  intruding  granite  and  pegmatite. 

Gold. — Sparingly  present  in  the  Blue  Hill  mines  and  reported  in  small  quan- 
tities from  most  of  the  other  mines  visited.  Occurs  sparingly  in  some  river 
gravels.     Not  an  abundant  ore  mineral  in  Maine. 

Graphite. — Occurs  in  pegmatite  and  in  metamorphosed  schists  at  several 
localities. 

Gypsum. — Present  in  ore  of  Sullivan  mine. 

Hematite.— E.it'hev  hematite  or  the  hydrated  oxide  turgite  is  usually  present 
in  the  oxidized  ore  of  all  groups. 

Jiao/i«.— Formed  from  feldspar  and  other  minerals  in  the  igneous  rocks  by 
reactions  with  surface  waters. 

Limonite. — The  most  abundant  mineral  in  the  oxidized  ore.  Appears  near 
the  surface  of  nearly  all  the  deposits. 


24  SOME    OEE   DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 

Magnetite. — Occurs  in  noticeable  quantity  in  the  Blue  Hill  copper  ores  and 
in  the  Deer  Isle  zinc  ore.  Minute  specks  are  present  in  the  ore  of  some  of  the 
later  silver  lodes  but  only  as  the  merest  traces. 

Malachite. — Rare  in  the  copper  deposits  of  Blue  Hill.  Forms  on  the  old 
slag  dumps,  but  was  not  noted  in  the  ore.  A  little  is  present  in  the  copper  pros- 
pects at  Pembroke. 

Manganese  oxide. — Present  in  the  oxidized  ore  at  Blue  Hill  and  occurs  in  the 
Lubec  lead  ore. 

MicrocUne. — See  Orthoclase: 

Molyddenite. — Present  in  granite  and  in  pegmatite  at  Catherine  Hill. 

Mtiscovitc. — Occurs  in  the  quartz-biotite  schist  and  is  associated  with  the 
ores  of  that  rock.  Forms  as  sericite  along  the  silver  lodes  by  metasomatic  re- 
placement, but  not  abundantly. 

Olivine. — Fresh  olivine  is  abundant  in  the  later  trap  rocks  and  decomposed 
olivine  in  the  greenstones. 

Orthoclase. — Orthoclase  and  microcline  are  prominent  minerals  of  the  granite 
and  associated  pegmatites. 

Pyrite. — The  most  abundant  and  a  ubiquitous  mineral  of  the  ores. 

Pyroxene. — Present  in  the  more  basic  igneous  rocks. 

Pyrrhotite. — Present  in  all  of  the  copper  ores  at  Blue  Hill  and  in  some  of  the 
lead  and  zinc  ores  near  by,  and  sparingly  present  in  the  Bingham  zinc  ore. 
Not  present  in  the  silver  lodes  associated  with  the  granite. 

Quarts. — Present  in  most  of  the  igneous  rocks,  in  all  of  the  sedimentary 
rocks,  and  in  the  ore  of  all  groups  of  deposits.  The  pegmatitic  quartz  con- 
tains fluid   inclusions. 

Rhodochrosite. — Absent  in  most  deposits;  a  little  noted  .at  the  Deer  Isle 
zinc  mine. 

Sericite. — See  Muscovite. 

Siderite. — Gangue  mineral  at  the  Pembroke  copper  prospects. 

Sih^er,  native. — Reported  from  the  Eggemoggin  and  Sullivan  mines. 

Specularite. — Nowhere  abundant.  Some  was  noted  at  the  Stewart  copper 
mine  and  on  the  Hercules  dump. 

8tej)hanite. — Reported  from  the   Sullivan  mine. 

StiMMe. — Reported  from  the  Sullivan  mine  and  from  the  copper  deposits 
near  Blue  Hill. 

Talc. — Present  in  ore  of  Sullivan  mine. 

Tetrahedrite. — Reported  from   the  Sullivan  mine. 

Tourmaline. — Present  in  the  pegmatite  at  Mount  Mica  and  at  Crocker  Hill. 

Tremolite. — Developed  in  the  wall  rock  at  the  Tapley  mine. 

Wolframite. — Dr.  Charles  T.  Jackson'*  found  wolframite  (iron-manganese 
tungstate)  and  molybdenite  in  granite  near  Blue  Hill  Falls, 

Zinc  tlende. — Present  in  deposits  of  all  groups,  but  sparingly  so  in  the  Blue 
Hill  copper  deposits. 

DISTRIBUTION  OF  OUTCROPS. 

In  relatively  late  geologic  times  the  entire  State  of  Maine  was 
covered  with  an  immense  glacier  or  ice  sheet  which  had  slowly  in- 
vaded it  from  the  northwest.  Much  of  the  territory  now  under  the 
sea  was  doubtless  overlain  by  this  ice  sheet,  for  it  is  known  to  have 
extended  to  far  outlying  islands.  As  the  climate  grew  warmer  the 
ice  gradually  receded  northwestward,  but  upon  the  country  it  had 

«  First  report  on  the  geology  of  the  State  of  Maine,  vol.  1,  p.  103. 


OXIDATION   AND   SECONDARY  ENRICHMENT.  25 

covered  it  left  drift  of  various  types  which  concealed  many  outcrops 
of  rocks  and  their  contained  ore  deposits.  After  the  ice  had  gone  the 
land  slowly  rose  to  higher  levels  above  the  sea.  At  some  places  sea- 
worn  pebbles  are  found  as  much  as  225  feet  above  the  present  coast." 
The  emergence  of  the  land  was  very  slow,  however,  and  at  times  it 
remained  stationary  long  enough  for  imperfect  bars,  spits,  and  simi- 
lar coast  features  to  be  formed.^ 

In  some  places  in  the  region  of  Penobscot  Bay,  when  the  land  was 
about  20  or  25  feet  below  its  present  position,"  there  was  a  note- 
worthy halt  in  the  process  of  elevation,  and  during  this  period  ter- 
races were  built  by  the  sea  and  cliffs  were  cut  in  exposed  places. 
Doubtless  the  glacial  drift  was  washed  away  at  many  places,  laying 
bare  the  rocks  and  ore  deposits.  Subsequently  the  land  rose  20  or  25 
feet.  Thus  along  the  ragged  seacoast  about  25  feet  above  the  present 
shore  line  was  exposed  a  belt  which  had  at  favorable  places  been 
lately  washed  by  the  waves.  Along  this  belt  the  rocks  are  well  ex- 
posed, and  in  it  many  of  the  ore  deposits  have  been  discovered.  The^ 
Deer  Isle,  Eggemoggin,  Hercules,  Emerson,  Cape  Rozier,  Sullivan, 
Denbow  Point,  Lubec,  and  other  deposits  are  near  the  water's  edge, 
not  more  than  a  few  feet  above  sea  level,  and  some  of  them  doubtless 
owe  their  exposed  condition  to  the  washing  of  the  waves  in  this  zone 
of  delayed  emergence.  Some  of  the  deposits  named  were  discovered 
below  high  tide  and  worked  by  means  of  cofferdams,  but  most  of  them 
were  found  some  10  to  20  feet  above  high  tide. 

In  many  regions  creeks  and  brooks  Avhich  cut  through  the  over- 
lying mantle  of  soil  furnish  good  exposures  of  the  rocks,  and  the 
banks  along  such  streams  are  favorable  positions  to  search  for  out- 
crops of  ore  deposits.  In  Maine,  however,  these  smaller  streams  have 
been  engaged  in  removing  the  glacial  material  left  at  the  compara- 
tively late  recession  of  the  ice  sheet  and  have  not  had  sufficient  time 
to  do  much  cutting  in  the  solid  rock;  consequently,  their  banks  do 
not  furnish  the  customary  quota  of  outcrops.  At  some  places,  where 
the  glacial  ice  with  its  included  stones  planed  off  the  country  rock, 
the  latter  has  not  yet  disintegrated  into  soil  and  still  remains  bare; 
in  such  places  a  few  deposits  have  been  discovered,  among  which  are 
the  Tapley  mine,  in  Brooksville,  and  some  of  the  copper  prospects  in 
Pembroke. 

OXIDATION  AND  SECONDARY  ENRICHMENT. 

When  sulphide  ores  remain  for  a  long  time  near  the  surface  of 
the  earth  the  oxygenated  surface  waters  react  on  their  minerals. 
Oxides,  carbonates,  and  other  compounds  are  formed,  and  the  quartz 

"  stone,  G.  H.,  Mon.  U.  S.  Geol.  Survey,  vol.  34,  1890,  p.  48. 
>>  Willis,  Bailey,  Bull.  Geol.  Soc.  America,  vol.  14,  1903,  p.  205. 

<^  Smith,  George  Otis,  Bastin,  E.  S.,  and  Brown,  C.  W.,  Penobscot  Bay  folio  (No.  149), 
Geol.  Atlas  U.  S.,  U.  S.  Geol.  Survey,  1907,  p.  13. 


26  SOME    ORE   DEPOSITS   IK    MAINE   AND    NEW    HAMPSHIRE. 

and  other  difficultly  soluble  minerals  are  usually  disintegrated.  As 
a  result  of  these  processes  the  outcrop  of  a  sulphide  ore  body  appears 
in  general  as  a  mass  of  iron  oxide  or  of  quartz  stained  with  iron  oxide 
and  other  oxygen  compounds.  In  cupriferous  deposits  carbonates 
commonly  appear  at  the  outcrop,  but  such  are  rare  in  the  oxidized 
copper  ores  in  Maine. 

The  depth  to  which  the  oxides  extend  is  variable  and  depends 
largely  on  the  shattering  or  fracturing  of  the  sulphide  deposits, 
which  makes  them  more  pervious  to  water,  and  on  the  length  of  time 
they  have  been  exposed  to  surface  waters.  In  Maine  the  deposits  are 
not  greatly  fractured,  and  since  glaciation  is  of  relatively  recent  date 
they  have  not  been  long  exposed  to  highly  oxygenated  surface  waters. 
At  many  jjlaces  the  sulphides  appear  at  the  very  surface,  and  mixed 
oxides  and  sulphides  are  very  common  in  the  outcrops.  At  the  Doug- 
las mine,  in  the  open  pit  just  west  of  the  main  shaft,  the  oxidized 
ore  ends  abruptly  along  a  fracture  which  cuts  the  lode  5  or  10  feet 
below  the  outcrop.  In  the  Milan  mine  (New  Hampshire)  the  depth 
of  oxidation  is  greater  and  the  lode  is  partly  oxidized  to  40  feet  below 
the  apex,  while  oxidation  along  watercourses  extends  100  feet  below 
the  surface.  Compared  with  that  of  deposits  in  unglaciated  regions 
oxidation  in  northern  New  England  is  slight. 

Where  the  upper  portion  of  a  lode  is  in  the  zone  of  oxygenated 
waters,  some  of  the  minerals  pass  into  solution.  Pyrite  and  chalco- 
pyrite  on  oxidation  yield  sulphuric  acid  and  iron  and  copper  sul- 
phates. If  it  happens  that  a  lode  is  highly  shattered  below  the  zone 
of  oxidation  these  sulphates  are  carried  downward  in  solution,  and 
when  they  reach  a  zone  in  which  there  is  relatively  little  oxygen  they 
react  with  pyrite  and  chalcopyrite  and  deposit  chalcocite.  This  proc- 
ess is  commonly  termed  secondary  enrichment,  for  it  changes  the 
lower-grade  sulphides  to  richer  copper  ores.  In  the  Milan  mine 
the  process  has  operated  to  some  extent  to  enrich  shalloAv  chalcopy- 
rite and  cupriferous  pyrite;  and  masses  of  these  minerals  where 
fractured  are  commonly  coated  with  a  film  of  black  chalcocite. 
Similar  ore  was  observed  on  the  dumps  of  the  Douglas  mine,  near 
Blue  Hill,  and  at  other  mines  near  by,  but  there  is  no  evidence  that 
this  process  was  carried  far.  The  tight  condition  of  the  deposits 
and  the  brief  period  of  exposure  to  oxygenated  waters  are  unfavor- 
able to  much  sulphide  enrichment  or  to  extensive  oxidation,  and  if  the 
deposits  extend  downward  to  great  depths  the  copper  content  will 
not  be  much  lower  than  it  is  near  the  surface. 

FUTURE  OF  THE  MINES. 

Lead^  zinc,  and  silver. — It  does  not  appear  likely  that  any  of  the 
lead,  zinc,  and  silver  deposits  which  have  been  examined  will  become 
important  sources  of  these  metals.  Possibly  some  of  them  could  be 
worked  in  a  small  way  by  hand  sorting  and  by  the  more  simple 


SUMMARY   OF   GEOLOGIC   EESULTS.  27 

methods  of  jiiechanical  concentration,  but  the  ore  is  in  the  main  of 
low  grade.  It  is  nowhere  greatly  oxidized  and  could  easily  be  con- 
centrated mechanically,  but  no  ore  body  yet  developed  is  of  sufficient 
size  to  warrant  the  erection  of  a  plant  large  enough  to  work  with  real 
economy.  A  presumption  against  the  existence  of  rich  deposits  asso- 
ciated with  granite  is  afforded  by  the  chloritic  alterations  of  the  walls 
along  the  veins — alterations  supposedly  due  to  the  ore-depositing 
solutions  given  off  by  the  granite  as  it  solidified.  Chlorite  is  formed 
extensively  by  regional  dynamometamorphic  processes,  to  some  ex- 
tent in  contact  metamorphism,  and  as  a  secondary  mineral  by  hydro- 
thermal  metamorphism  of  the  wall  rocks  along  certain  productive 
lodes  in  diabase  and  other  basic  rocks.  Where  associated  with  fissure 
veins  in  acidic  rocks,  it  has  generally  been  formed  by  the  w^eaker  ore- 
bearing  solutions ;  and  in  regions  of  large  and  rich  deposits  it  is  found 
some  distance  away  from  the  veins,  in  places  where  apparently  the 
solutions  had  already  spent  too  much  of  their  power  to  change  the 
country  rock  greatly  and  to  deposit  ore.  Again,  near  the  great  vein 
deposits  the  w^all  rock  has  commonly  undergone  strong  sericitization, 
pyritization,  silicification,  and  other  processes;  and  these  were  rela- 
tively inactive  when  the  lead,  zinc,  and  silver  veins  associated  with 
the  intruding  granite  were  formed  and  were  not  strongly  active  when 
the  ores  associated  with  the  trap  rocks  were  deposited. 

Copper. — The  pyritiferous  deposits  near  Blue  Hill  are  not  at  pres- 
ent sufficiently  exposed  to  warrant  an  estimate  of  their  value,  but  a 
deposit  which  is  in  many  respects  similar  is  now  successfully  worked 
at  Milan,  N.  H.  (See  p.  50.)  To  judge  from  the  mineral  composi- 
tion at  that  place,  it  would  seem  that  somewhat  similar  methods  could 
be  applied  to  the  Blue  Hill  ores.  These  ores  or  concentrates  from 
them  would  be  rich  in  sulphur  and  could  without  doubt  be  sold 
advantageously  to  acid  works.  If  the  paper  mills  of  New  England 
should  ever  adopt  the  practice  followed  at  some  European  plants, 
they  could  make  their  sulphur  dioxide  at  a  lower  cost  for  the  raw 
material  from  pyrite  than  from  native  sulphur,  a  large  tonnage  of 
which  is  now  utilized  in  paper  manufacture.  The  schistose  garnetif- 
erous  sulphide  ore  at  Deer  Isle  has  proved  refractory  to  metallurgical 
treatment,  but  possibly  one  of  the  newer  methods  of  oil  flotation  could 
be  successfully  employed  to  separate  the  garnet  from  the  sulphides 
if  the  amount  of  ore  exposed  is  sufficient  to  warrant  an  installation. 

SUMMAaY  OF  GEOLOGIC  EVENTS  AS  RELATED  TO  ORE  DEPOSITS. 

From  studies  of  the  geology  of  the  Penobscot  Bay  quadrangle,'^  the 
Perry  Basin,^  and  other  areas,  and  from  the  observed  relations  of  the 
ore  deposits,  the  geologic  events  related  below  are  deduced. 

"Smith,  G.  O.,  Bastin,  B.  S.,  and  Brown,  C.  W.,  Penobscot  Bay  folio  (No.  149),  Geol. 
Atlas  U.  S.,  U.  S.  Geol.  Survey,  1907. 

"  Smith,  G.  O.,  and  White,  David.  Prof.  Paper  U.  S.  Geol.  Survey  No.  35,  1905. 


28  SOME    OEE   DEPOSITS   IN    MAINE   AND   NEW   HAMPSHIRE. 

Pre-G amhrian  and  Cambrian  time. — In  pre- Cambrian  or  possibly 
in  early  Cambrian  time  a  series  of  siliceous  shales  and  impure  sand- 
stones were  laid  down  in  extensive  beds  and  were  subjected  to  re- 
gional metamorphism.  Later,  probably  in  Cambrian  time,  the  im- 
pure sand  which  now  forms  the  slates  of  the  Islesboro  formation  was 
deposited.  During  the  deposition  of  this  formation  great  volcanic 
activity  prevailed;  the  acidic  Castine  rocks,  which  included  both 
flows  and  dikes  and  some  calcareous  water-laid  tuffs,  were  formed. 
These  were  followed  very  closely  or  perhaps  in  part  were  accompanied 
by  the  North  Haven  eruptives.  These  North  Haven  diabases,  basic 
trachytes,  and  albite-augite  syenites  included  both  effusive  and  intru- 
sive bodies.  The  garnetiferous  zinc  ores  at  the  Deer  Isle  mine,  which 
are  in  a  calcareous  phase  of  the  Castine  near  the  contact  of  the  North 
Haven  greenstone,  were  probably  formed  by  processes  of  contact 
metamorphism  during  North  Haven  time,  and  part  or  all  of  the  Blue 
Hill  and  Brooksville  pyritiferous  copper  ores  are  believed  to  have 
been  formed  at  the  same  period  or  in  connection  with  the  Castine 
eruptions.  Near  the  close  of  the  period  regarded  as  Cambrian  and 
following  closely  the  igneous  activity,  the  Coombs  limestone,  a  mem- 
ber of  the  Islesboro  formation,  the  Battle  quartzite,  and  the  slates  of 
the  Penobscot  formation  were  successively  laid  down. 

After  the  eruptions,  after  the  copper  and  the  zinc  ores  were  de- 
posited, and  after  the  Penobscot  beds,  which  later  became  slates,  were 
laid  down,  the  region  was  subjected  to  profound  dynamic  metamor- 
phism. A  schistose  structure  was  developed  in  all  of  the  rocks,  but 
is  most  marked  in  those  containing  the  most  clay.  The  ore  bodies 
also  took  on  a  schistose  structure.  As  a  result  of  this,  in  the  Deer  Isle 
zinc  deposit  garnet,  amphibole,  quartz,  sulphides,  and  magnetite  were 
compressed  into  thin  crumpled  parallel  bands.  The  copper  deposits 
also  were  greatly  affected,  but  since  these  were  simpler  in  mineral 
composition  the  resulting  deposits  were  different.  At  the  center 
of  the  deposits  the  large  and  relatively  j)ure  masses  of  pyrite  were 
broken  and  recemented  with  pyrite  and  chalcoi^yrite.  Where  there 
was  a  higher  percentage  of  quartz  with  the  pyrite  the  two  min- 
erals were  broken  into  unequidimensional  fragments  and  these 
oriented  themselves  in  lines  parallel  with  the  schistosity.  Where 
considerable  clayey  material  was  present  chlorite  and  the  micas 
formed  in  great  abundance  and  oriented  themselves  with  their  long 
directions  nearly  parallel  with  the  schistosity  and  parallel  to  the 
long  dimensions  of  quartz  and  pyrite  fragments.  AVhere  a  pyrite 
crystal  was  protected  by  a  cover  of  clayey  material  it  did  not  break, 
but  the  micaceous  minerals  formed  inclosing  spheres  around  it  and 
bent  to  accommodate  themselves  to  it;  but  where  such  a  pyrite 
crystal  Avas  pushed  through  the  chlorite  against  another  crystal  of 
pyrite,  both  were  shattered.     There  was  much  recrystallization  and 


SUMMARY    OF    GEOLOGIC    KKSULTri.  29 

some  pyrite  was  redeposited  as  perfect  crystals.  Quartz  se(Miis  also 
to  have  been  dissolved  and  reprecipitated  to  some  extent,  but  not  in 
crystal  form.  Dnring  metamorphism  some  of  the  ore  bodies  were 
probably  separated  by  a  peculiar  kind  of  faulting,  which  must  have 
taken  place  at  a  depth  that  was  in  the  zone  of  flow  for  the  wall 
rock  and  the  zone  of  fracture  for  the  ore.  Such  a  fault,  as  illustrated 
by  the  Milan  mine  (see  p.  50),  is  strikingly  sigmoidal  and  laps 
around  both  of  the  ends  of  the  broken  ore  body,  the  schistosity  fol- 
lowing its  complexly  curving  plane,  as  shown  by  figure  4.  The 
overlapping  lenses  which  are  said  to  constitute  some  of  the  Blue  Hill 
deposits  probably  resulted  from  similar  movements.  Just  when 
these  events  happened  is  not  known,  but  they  were  before  the  begin- 
ning of  the  deposition  of  the  Ames  Knob  formation,  which  lies  un- 
conformably  above  the  metamorphosed  series.  The  Ames  Knob  is 
of  Silurian  age  (Niagaran)  and  is  not  metamorphosed,  its  lowest 
member  being  a  basal  conglomerate  which  contains  well-rounded 
pebbles  of  black  and  green  slates,  quartzites,  and  vein  quartz."  The 
metamorphosed  rocks  and  ore  deposits  are  therefore  older  than  the 
Silurian,  but  how  much  older  is  not  known. 

Silvrian  time. — ^AHiile  the  Silurian  rocks  were  being  deposited 
volcanic  forces  again  became  active.  The  Thorofare  andesite  was 
erupted  and  was  followed  by  the  Vinalhaven  rhyolite.  At  about  this 
time  gentle  folding  and  some  faulting  took  place,  accompanied  or 
followed  by  the  great  intrusions  of  granite  and  diorite.  The  intruded 
rocks  were  metamorphosed  to  some  extent,  though  not  profoundly,  by 
the  gases  and  solutions  given  off.  The  granite  intrusions  all  along 
the  coast  were  probably  formed  at  about  the  same  time,  and  if  so 
they  are  of  post-Niagaran  or  early  Devonian  age,  for  pebbles  of  the 
granite  are  found  in  the  late  Devonian  (Perry  formation).  It  seems 
that  the  granites  were  in  the  main  poor  in  metals,  but  some  of  their 
pegmatitic  phases  carried  a  little  molybdenum  sulphide,  w^hich  was 
deposited  when  the  pegmatites  solidified.  Quartz  veins  were  de- 
posited also  by  solutions  which  originated  in  the  granite.  Some  of 
these  veins  were  barren,  but  some  carried  ores  of  silver,  zinc,  and 
lead.  The  Sullivan  silver  veins,  which  are  in  the  Ellsworth  schist, 
were  deposited  at  this  time,  and  the  Gouldsborough  zinc-silver  lode 
in  diorite  is  presumably  of  the  same  age.  The  mineralizing  solutions 
altered  the  wall  rock  to  chlorite,  epidote,  and  sericite,  but  this  action 
was  not  intense.  The  galena-feldspar  ore  in  a  prospect  on  the  Owen 
farm  at  Blue  Hill  appears  to  have  consolidated  directly  from  the 
granite. 

Devonian  time. — After  the  granite  had  solidified  it  was  eroded ; 
and  above  it  the  lower  conglomerate  member  of  the  Perry  formation 
was  laid  down  in  late  Devonian  time.     Subsequently  basic  lavas  were 


«  Smith,  Bastin,  and  Brown,  folio  149,  1907,  p.  4. 


30  SOME    OKE   DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 

extra vasated  upon  these,  and  upon  the  lavas  Denovian  sandstones  were 
deposited,  which  were  in  turn  overflowed  by  vesicular  basic  lavas. 
In  connection  with  the  same  general  period  of  basic  eruptives,  and 
probably  in  late  Devonian  time,  the  Lubec,  Denbow  Point,  and  Fern- 
broke  lead  and  zinc  deposits  are  believed  to  have  been  formed.  Still 
later — probably  in  Mesozoic  time — basaltic  dikes  cut  the  various 
formations;  at  Concord,  in  Somerset  County,  an  ore  deposit  which 
in  general  character  most  closely  resembles  those  associated  with  the 
granular  intrusives  is  cut  by  such  a  dike. 

Quaternary  time. — Other  events  that  affected  the  ore  deposits  in 
Mesozoic  or  in  Tertiary  time  are  not  known.  If  the  deposits  exposed 
to  Aveathering  were  deeply  oxidized  during  those  periods  then  the 
oxidized  portions  were  planed  off  by  the  great  ice  sheet  which 
covered  the  country  in  Pleistocene  time.  In  Recent  time,  however, 
since  the  retreat  of  the  ice,  the  sea  has  cut  cliffs  in  which  many  of 
the  deposits  are  exjDOsecl,  and  as  a  result  the  seashore  has  become  a 
favorable  j)lace  for  outcrops.  The  copper  lodes,  where  fractured, 
have  been  to  a  very  tri^dal  extent  leached  by  descending  surface 
waters,  which  have  dejaosited  chalcocite  films  on  the  older  sulphides, 
but  these  lodes  were  presumably  so  completely  recemented  during  the 
period  of  regional  metamorphism  and  have  been  disturbed  so  little 
since  that  time  that  they  have  not  been  greatly  affected  by  the 
processes  of  chalcocitization.  Some  oxidation  has  taken  place,  but 
as. a  rule  it  has  extended  to  only  slight  depths — generally  to  not  more 
than  a  few  feet  below  the  outcrop. 

DESCRIPTIONS  OF  MINES. 
HANCOCK   COUNTY. 
GENERAL    STATEMENT. 

The  southwestern  part  of  Plancock  County  has  been  geologically 
mapped  in  detail  by  George  Otis  Smith,  E.  S.  Bastifi,  and  C.  W. 
Brown  in  the  Penobscot  Bay  folio  (No.  149)  of  the  Geologic 
Atlas  of  the  United  States,  published  by  the  United  States  Geolog- 
ical Survey.  Plate  II  of  the  present  paper  is  a  reproduction  of  a  part 
of  the  geologic  map  of  this  folio,  with  the  addition  of  symbols  indi- 
cating the  positions  of  the  mines  in  the  district.  Figure  10  is  a  section 
showing  the  relations  of  the  rocks  along  the  line  A-A'  in  the  plate, 
but  extending  beyond  it,  and  figure  11  is  a  section  along  the  line  B-B'. 

The  principal  rocks  with  which  the  ores  are  associated  are  the 
Ellsworth  schist,  the  schistose  volcanic  rocks,  and  the  granite  and 
closely  related  diorite.  The  relatively  small  area  of  Ellsworth  schist 
at  Blue  Hill  includes  nearly  all  of  the  schistose  dejDOsits  of  pyritic 
copper  ores.    A  large  area  of  quartzose  schist  extends  northwestward 


U.  S.  GEOLOGICAL   SURVEY 


BULLETIN    432       PLATE    II 


II-  1     T     H 


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GBOIiOGIC  MAP  or  THE  MINERALIZED  AREA  OF  BLUEHILL,  BROOKSVILIiE,  DEER  ISLE, 

AND   CASTINE,  MAENE 

Scale    r260oo 


H.M.Wilson,  Geographer  In  charg. 
Topograph_y  by  U.S. Coast  and 
Geodetic  Survey,  W.  H.Lovell,and 
Hersey  fvlunroe. 
Triangulation  by  US. Coast  and 
Geodetic  Survey 

Surveyed  in  1900-1903. 


SEDIMENTARY    ROCKS 


&;  5  KiloiDLeljers 


Geology  by  George  Otis  Smith, 
E.S.Bastin.and  C.W.Brown. 
Surveyed  in  1902-1904. 


Conto-ux*  irrtexTral  20  feet. 

nation  is  m&an    een,   leveX. 

1909 


LEGEND 


IGNEOUS   ROCKS 


CAMBRIAN  7 


€i 


CAMBRIAN  OR  PRE-CAMBRIAN 
A 

^ 

^ 

ev/ 

DEVONIAN  ? 


CAMBRIAN  ? 


CoTttempcfraneous  ivitTi  Tippisrjiart 
OT  Isleshoro  formatioTi 


^fer 


Islesboro  foimaiioii      EUswortb.   sdrLst     Biotite  drauite        Dioiite,  diabcLSe,  Seipentine 

(slca^san^adhtstslocaHv  fcrujnf>le^ gr^im.  onA  fiiju^Tn,e^zU77i.,a7uiooars&  aXLcL ^ 8Lbl>rO 


Noilli  Haven.  Castme  fonxia.tLon 

greeiLS>XOILe  ^iu.oixujrnng  as  flovs. 


anAoocxiawnjaZly  pur& 


^  Mne  5<  Qioarry  cX.  Grav^el  pit 


HANCOCK    COUNTY. 


from  Fi-enchniaii  Bay  along  Union  River  far  to  the 
north  of  Ellsworth.  This  area  includes  the  mines  at 
Sullivan  and  Franklin. 

The  schistose  igneous  rocks  which 
belong  to  the  Castine  formation  cover 
extensive  areas  in  the  western  part  of 
the  region  represented  on  Plate  11. 
The  Tapley  mine,  which  in  many  re- 
spects resembles  the  Blue  Hill  copper 
deposits,  is  inclosed  in  the  Castine,  and 
the  Deer  Isle,  Eggemoggin,  Cape 
Rozier,  Hercules,  Emerson,  and  other 
deposits  are  in  the  same  formation. 
The  granites  and  associated  diorite 
which  are  intrusive  in  the  schistose 
rocks  cover  a  large  part  of  the  area 
represented  on  Plate  II,  but  in  this 
area  the  only  deposit  known  which  is 
genetically  related  to  the  granular 
rocks  is  at  the  Owen  lead  prospect. 

In  the  eastern  part  of  the  county,  at 
Sullivan  and  at  Franklin,  fissure  veins 
of  silver  ore  which  cut  the  schist  near 
granite  contacts  have  been  deposited 
by  solutions  which  are  believed  to  have 
had  their  origin  in  the  granite.  Still 
farther  east,  the  Gouldsborough,  a  lode 
of  argentiferous  zinc  blende  in  diorite 
is  supposed  to  have  had  a  similar  gene- 
sis, and  just  east  of  the  Hancock 
County  line  at  Cherryfield  a  zinc  de- 
posit is  inclosed  in  schist  not  far  from 
granite  to  which  it  may  be  genetically 
related.  The  molybdenite  deposits  of 
Catherine  Hill  are  associated  with  peg- 
matite veins  which  cut  the  granite. 

DOUGLAS    MINE. 


,t^        The  Douglas  mine,  located  about  2 
,  ^  miles  southwest  of  Blue  Hill  village, 
^  ^'^       is  owned  by  interests  identified  with 

the  Pittsburg  and  Montana  Company,  of  Butte.     The 


>^^: 


*.  a 


mine  was  opened  in  1878  and  was  worked  until  1883 
and  is  said  to  have  produced  between  two  and  three 


1 


SSjs 


32  SOME    ORE   DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 

million  pounds  of  copper  which  yielded  about  $300,000.  It  was 
reopened  in  1908  and  sampled  by  its  present  owners.  A  two-com- 
partment shaft  inclined  47°  is  sunk  245  feet  on  the  incline.  A  second 
two-compartment  shaft,  about  150  feet  to  the  east,  is  sunk  to  a  depth 
of  75  feet.  Both  were  under  water  when  the  mine  was  visited.  The 
deep  shaft  is  equipped  with  steam  power  and  skip.  On  the  surface 
are  numerous  heaps  of  roasted  ore  and  the  ruins  of  a  concentrator, 
blast  furnace,  precipitation  plant,  and  refining  furnace.  The  deposit 
is  a  lode  said  to  be  from  12  to  20  feet  wide,  striking  eastward  and 
dipping  about  45°  S. 

An  analysis  of  the  better  grade  of  ore  made  for  the  company  by 
S.  P.  Sharpies,  of  Boston,  is  given  below : 

Analysis  of  copper  ore  from  the  Douglas  mine. 

Si02 35.  8 

Fe  -___ 25.  9 

CaO .13  • 

Mn .  52 

Al=03 - 3. 11 

S  -_ 28 

Cul 5.  88 

99.34 

This  ore  carries  0.01  ounce  gold  and  1.17  ounces  silver  to  the  ton. 

The  country  rock  is  a  rather  siliceous  phase  of  the  Ellsworth  schist 
and  is  composed  of  quartz,  muscovite,  and  biotite,  with  pyrite  scat- 
tered liberally  through  it.  Where  exposed  in  an  open  cut  a  few  feet 
west  of  the  main  shaft  the  lode  follows  the  schistositj^  of  the  country 
rock.  The  ore  minerals  observed  in  the  pit  and  on  the  dump  are 
pyrite,  chalcopyrite,  pyrrhotite,  chalcocite,  arsenopyrite,  zinc  blende, 
magnetite,  and  cuprite.  Stibnite.  tennantite,  and  tetrahedrite  have 
also  been  reported."  The  gangue  minerals,  which  in  places  are 
banded  with  the  sulphides,  are  quartz,  sericite,  biotite,  and  chlorite. 
A  little  molybdenite  is  present,  with  pyrite  and  muscovite.  Thin 
sheets  of  native  copper  are  reported  to  have  formed  in  joint  seams  of 
the  ore.  Oxidation  in  the  open  pit  is  nearly  complete  to  a  dejoth  of 
5  feet  and  ends  at  a  prominent  joint  plane  which  dips  to  the  south 
at  a  very  low  angle. 

TWIN  LEAD  MINE. 

The  Twin  Lead  mine  is  on  the  Sargentville  road  about  1|-  miles 
southwest  of  Blue  Hill.  A  three-compartment  inclined  shaft  now 
filled  with  water  is  reported  to  be  200  feet  deep.     The  lode  has  been 

"  Smock,  J.  C,  Mineral  Resources  U.  S.  for  1882,  U.  S.  Geol.  Survey,  1883,  p.  687. 
Bartlett,  F.  L.,  Mines  of  Maine,  p.  23. 


HANCOCK    COUNTY.  33 

stoped  out  open  cast  to  a  depth  of  12  feet  for  about  70  feet  along  the 
strike.  The  ruins  of  a  smelter  and  small  slag  dump  show  that  some 
ore  has  been  treated.  The  lode,  which  is  about  10  feet  wide,  is  in  the 
Ellsworth  formation  and  parallels  the  schistosity,  striking  N.  77°  E. 
and  dipping  about  45°  S.  The  ore  minerals  are  pyrite,  pyrrhotite, 
magnetite,  chalcopyrite,  and  a  little  bornite.  The  gangue  minerals 
are  quartz,  sericite,  biotite,  and  chlorite.  The  sulphides  outcrop  at 
the  surface  and  oxidation  is  inconsiderable.  The  pyrite  is  dissem- 
inated through  the  rock  and  in  bands  parallel  to  the  schistosity,  but 
lenses  of  ore,  consisting  mainly  of  pyrite,  chalcopyrite,  and  quartz, 
are  found  here  and  there  in  the  lode.  A  stringer  of  pyrite,  making 
off  from  the  main  lode,  is  shown  in  figure  3;  its  associations  show 
that  the  quartz  and  pyrite  are  older  than  the  metamorphism  of  the 
schist,  a  fact  also  indicated  by  the  arrangement  of  the  minerals  in 
the  lower-grade  ore. 

BLUE  HILL  MINE. 

The  Blue  Hill  mine  is  located  1,050  feet  west  of  the  Tw^in  Lead 
mine,  on  the  opposite  side  of  the  road.  Large  dumps  of  ore  and  coun- 
try rock  similar  to  that  of  the  Twan  Lead  surround  the  ruins  of  a 
shaft,  and  roasted  heaps  of  ore  lie  near  by.  Near  the  mine  are  the 
ruins  of  a  concentrating  mill,  and  below  this  are  the  ruins  of  a  smelter 
and  slag  dump.  The  lode  is  not  accessible  above  or  under  ground. 
At  the  low  hill  just  south  of  the  mine  a  75-foot  tunnel  is  driven  east- 
ward in  pyrite-bearing  schist  cut  by  large  masses  of  white  quartz. 
Southwest  of  this  tunnel,  on  the  southwest  slope  of  the  hill  on  which 
the  Blue  Hill  mine  is  situated,  a  deep  open  cut  about  75  feet  long  and 
10  to  15  feet  wide  is  driven  S.  85°  E.  into  the  hillside.  The  country 
rock  is  quartzite  impregnated  with  pyri^^e  and  cut  by  numerous 
closely  spaced  veinlets  of  pyrite.  It  carries  also  some  large  masses 
of  nearly  pure  jjyrite  and  some  chalcopyrite. 

STEWART    3IINE. 

The  Stewart  mine  is  southeast  of  "Third  Pond,  between  this  and 
Second  Pond  and  about  100  yards  northeast  of  the  Douglas  mine.  A 
two-compartment  shaft  said  to  be  150  feet  deep  but  now  filled  with 
water  is  sunk  southward  at  an  inclination  of  57°  on  an  eastward- 
striking  lode.  The  ore  on  the  dump  is  similar  to  that  of  the  Twin 
Lead  but  is  more  siliceous.  About  150  feet  north  of  the  shaft  an- 
other lode  about  10  feet  wide  strikes  S.  87°  E.  and  dips  70°  to  80° 
S. ;  it  is  opened  in  a  long,  deep  cut  exposing  a  great  mass  of  pyritif- 
erous  rock.  The  country  rock,  which  is  the  Ellsworth  schist,  con- 
tains considerable  biotite,  but  is  more  siliceous  than  at  the  Blue  Hill 
and  Twin  Lead.  Actinolite,  tremolite,  biotite,  sericite,  chlorite,  and 
zircon  are  microscopically  visible.  Near  the  lode  the  quartzose  schist 
42381°— Bull.  432—10 3 


34  SOME    OEE   DEPOSITS   IX    MAIXE   AXD    XEW    HAMPSHIEE. 

carries  considerable  pyrite  and  some  clialcopvrite,  magnetite,  and 
pvrrhotite.  The  trend  of  the  deposit  agrees  with  the  schistosity  of 
the  rock,  and  as  at  the  Bhie  Hill  and  the  Twin  Lead  the  pyrite  bands 
are  crumpled  like  the  silicates,  showing  that  the  ore  was  deposited 
before  the  regional  metamorphism  of  the  country. 

MAMMOTH    MINE. 

The  Mammoth  mine  is  located  on  the  south  shore  of  Second  Pond, 
one-half  mile  from  the  Douglas.  A  vertical  shaft,  now  full  of  water, 
is  said  to  be  100  feet  deep.  The  country  rock  is  Ellsworth  schist, 
here  very  quartzitic.  The  gangue  is  quartz,  biotite,  muscovite,  and 
actinolite.  The  ore  minerals  are  pyrite.  chalcopyrite,  pyrrhotite.  and 
specularite.  with  a  very  small  amount  of  zinc  blende  and  galena. 
On  the  dump  are  several  hundred  tons  of  highly  pyritiferous  rock 
which  carries  a  noticeable  amount  of  the  copper  sulphides. 

OWEX    MIXE. 

The  Owen  mine  is  located  on  the  west  side  of  Second  Pond,  half 
a  mile  southwest  of  the  Douglas.  The  country  rock  is  a  siliceous 
phase  of  the  Ellsworth  schist  with  a  schistosity  that  strikes  S.  82°  E. 
and  dips  45°  S.  A  pit  2.5  feet  long  and  12  feet  wide  is  sunk  in  sul- 
phide ore  and  pyritiferous  quartzite  to  a  depth  of  30  feet.  The 
workings  do  not  show  the  direction  of  the  lode.  The  minerals  are 
quartz,  biotite,  sericite.  pyrite.  chalcopyrite,  pyrrhotite,  and  mag- 
netite. According  to  Mr.  Arthur  Owen  thin  sheets  of  native  copper 
have  been  found  in  joint  planes  of  the  rock.  The  ore  is  said  to  carry 
more  than  3  per  cent  of  copper. 

OWEX   LEAD   PROSPECT. 

The  Owen  lead  prospect  is  one-half  mile  west  of  the  Mammoth 
copper  mine  and  north  of  the  granite  batholith  which  cuts  siliceous 
Ellsworth  schist  near  by.  In  1909  the  small  pit  20  feet  deep  was 
full  of  water.  The  Ellsworth  here  is  composed  of  quartz,  biotite, 
muscovite,  and  other  minerals  and  is  cut  by  dikes  of  granite  wliich 
make  off  from  the  large  mass.  There  is  no  pronounced  contact  meta- 
morphism of  the  schists;  no  garnet  appears  to  have  been  formed; 
actinolite  is  rather  more  abundant  than  elsewhere;  magnetite  and 
pyrrhotite  are  developed  but  are  not  more  abundant  than  at  other 
places  in  the  schist  a  mile  or  more  away  from  the  contact,  where  they 
have  formed  through  d}Tiamometamorphism.  In  one  of  the  small 
granite  dikes  there  is  considerable  galena,  a  little  pyrite.  and  some 
chalcopyrite,  all  of  the  sulphides  being  intergrown  with  feldspar, 
quartz,  biotite,  and  muscovite.  Magnetite  or  pyrrhotite.  which  are 
common  in  the  copper  ores,  are  not  present  in  the  lead  ore. 


HANCOCK   COUXTT.  36 

TYliile  the  deposit  appears  to  be  small,  the  genesis  of  the  ore  is 
of  peculiar  interest.  The  granite  near  by  is  medium  grained  and 
is  composed  of  quartz,  feldspar,  biotite,  and  a  little  sericite.  The 
feldspars  are  orthoclase.  microcline,  and  a  little  albite.  The  galena- 
bearing  granite  is  not  coarse  like  most  pegmatites  but  is  of  medium 
grain  like  all  the  granite  near  bj'.  It  has  the  same  minerals  in  the 
same  proportion  except  that  albite,  a  small  amount  of  which  is 
present  in  the  granite,  is  even  less  abundant  in  the  ore.  The  galena, 
which  in  some  specimens  makes  up  one-fourth  or  more  of  the  mass, 
is  intergrown  with  the  feldspars  and  surrounds  well-formed  idio- 
morphic  feldspar  crystals,  the  sharp  corners  of  which  have  been 
rounded  off  before  the  galena  solidified.  A  little  apatite  is  also 
inclosed  in  galena  and  some  chalcopyrite  is  intergrown  with  galena. 
The  structure  is  the  same  as  in  some  diabases,  where  feldspar  crystals 
are  surrounded  by  a  matrix  of  augite.  but  in  the  granite  here  galena 
takes  the  place  of  augite.  A  photomicrogi'aph  of  a  thin  section 
of  this  ore  is  shown  in  Plate  I.  B.  Xone  of  the  minerals  are  highly 
altered,  but  some  chlorite  is  developed  by  decomposition  of  biotite  and 
the  feldsj)ar  is  slightly  clouded  by  decomposition  to  kaolin.  The 
white  mica  present  is  mainly  or  altogether  primary.  The  ore  is 
clearly  the  consolidation  of  a  molten  magma. 

GRAKGER    INIIXE. 

At  the  Granger  mine,  about  three-fourths  mile  south  of  Blue  Hill, 
a  shaft,  now  inaccessible,  is  sunk  in  the  Ellsworth  schist.  In  the 
ore  exposed  on  the  dmup  the  gangue  minerals  are  quartz,  biotite, 
chlorite,  and  sericite.  The  sidphides  noted  are  pyrite.  chalcopyrite, 
and  bornite. 

WEIL  FREDDIE  MIXE. 

The  Weil  Freddie  mine  is  a  few  rods  east  of  the  village  at  Blue 
Hill  Falls,-on  the  north  shore  of  the  bay.  An  inaccessible  shaft,  re- 
ported to  be  100  feet  deep,  is  sunk  in  pyritiferous  Ellsworth  schist 
which  carries  some  copper  j^yrite. 

TAPLEY   MINE. 

The  Tapley  mine  is  on  the  farm  of  Charles  P.  Tapley.  about  2^ 
miles  southwest  of  Brooksvilie.  It  was  opened  about  thirty  years 
ago  and  a  small  amount  of  ore  has  been  shipped  for  experimental  pur- 
poses. The  mine  changed  ownership  in  1907  and  some  development 
work  was  then  done,  but  these  operations  were  soon  suspended,  and  in 
1909.  when  the  property  was  visited,  the  mine  was  idle  and  the  under- 
ground workings  full  of  water.  A  shaft  is  sunk  on  the  lode  to  a 
depth  of  SO  feet  and  according  to  report  some  200  feet  of  drifts  and 


36  SOME    OEE   DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIEE. 

crosscuts  are  turned  from  it.  The  deposit  was  exposed  at  several 
places  in  open  cuts. 

The  country  rock  is  the  Castine  formation,  which  is  here,  in  the 
main,  a  rhyolitic  breccia,  but  which  locally  includes  a  dark  rock, 
presumably  andesite.  Both  of  these  rocks  are  regionally  meta- 
morphosed, with  the  development  of  secondary  biotite,  sericite,  and 
tremolite.  Small  colorless  garnets  are  developed  also  in  the  andesite. 
Some  of  the  rhyolite  contains  mmierous  specks  of  microscopic  magnet- 
ite and  in  hand  specimens  is  as  dark  as  the  andesite.  The  schistosity 
of  this  rock,  which  though  not  pronounced  is  well  defined,  strikes 
northeastward.  The  rhyolite  is  at  some  places  strongly  plicated  and 
cut  by  quartz  veinlets  which  cross  its  schistosity.  Northwest  of  the 
lode  a  dike  of  basalt  only  slightly  metamorphosed  cuts  the  Castine. 

The  deposits  outcrop  on  a  glaciated  surface.  For  500  feet  along  the 
lode  the  ground  is  cleared  and  open  cuts  are  dug  at  several  places. 
The  lode  strikes  N.  47°  E.,  parallel  to  the  schistosity,  and  is  a  wide 
zone  of  shattered  and  altered  rhyolite.  The  sulphides  are  p^^rite  and 
chalcop3'rite,  both  of  which  are  found  at  the  very  surface;  films  of 
limonite,  hematite,  cuprite,  and  bornite  appear  in  small  amount  in 
the  cracks  of  the  ore,  which  is  not  highly  shattered.  The  ore 
includes  fragments  of  the  country  rock  which  are  slightly  silicified, 
but  the  lum2:>s  of  pyrite  ore  on  the  dump  contain  but  little  quartz. 
These  fragments  contain  much  more  sericite  and  chlorite  than  the 
country  rock  a  few  feet  from  the  vein.  Some  of  the  ore  in  the  open 
pits  is  rhyolite  which  contains  secondary  tremolite,  sericite,  biotite, 
and  chlorite,  with  flakes  and  specks  of  pyrite,  the  latter  constituting 
perhaps  10  per  cent  of  the  mass.  A  little  magnetite  and  pyrrhotite 
is  present.  Some  of  the  ore  impregnated  with  pyrite  shoAvs  laminated 
sericite  and  quartz,  and  some  of  the  chalcopyrite  is  feebly  laminated 
parallel  to  the  micaceous  sheen  which  shows  when  the  ore  is  held  in 
suitable  position,  suggesting  that  the  sulphides  were  formed  before 
the  regional  metamorphosing  processes  had  ceased  operation.  This 
relationship  is  indicated  also  by  the  crumpled  stringers  of  pyrite 
which  are  found  near  the  lode.     One  of  these  is  shown  in  figure  2. 

EGGEMOGGIN    MINE. 

The  Eggemoggin  mine  is  at  tide  water  on  Bj^ard  Point,  about  a 
mile  west  of  Sargentville.  Two  shafts,  now  inaccessible,  are  sunk  in 
devitrified  rhyolite  breccia  of  the  Castine  formation.  The  lode  is 
not  exposed,  but  the  dump  showed  altered  rhyolite  impregnated  with 
sulphide  and  galena.  Some  of  it  is  strongly  sheeted  and  cut  by  par- 
allel stringers  of  white  quartz,  which  also  carries  sulphides.  The 
principal  minerals  are  quartz,  sericite,  pyrite,  arsenopyrite,  chalcopy- 
rite, galena,  and  zinc  blende.     The  ore  is  reported  to  carry  good 


HANCOCK   COUNTY.  37 

values  in  silver.  Native  silver  is  said  to  have  been  present.  Accord- 
ing to  report,  shipments  of  ore  were  made  in  the  late  eighties,  but  the 
mine  has  not  been  worked  for  many  years.  The  ruins  of  an  old 
metallurgical  plant  stand  near  by. 

DEER    ISLE    MINE. 

The  Deer  Isle  mine  is  located  at  tide  water  on  Dunham  Point,  about 
3  miles  west  of  Deer  Isle  village.  This  mine  was  first  worked  in  the 
seventies  and  was  reopened  in  1907,  since  when  it  has  produced  about 
900  tons  of  ore.  A  shaft  is  sunk  on  the  lode  at  an  inclination  of  45° 
to  a  depth  of  260  feet,  and  on  the  200-foot  level  drifts  about  100  feet 
long  are  turned  in  either  direction.  Near  the  shaft  stopes  are  carried 
up  within  a  few  feet  of  the  surface.  When  the  mine  was  visited  stopes 
below  the  100-foot  level  were  inaccessible. 

The  mine  is  in  the  Castine  formation,  presumably  an  altered  por- 
phyritic  rock  with  phases  which  were  probably  calcareous  water-laid 
tuff.  The  North  Haven  greenstone  outcrops  near  by  and  is  regarded 
as  of  approximately  the  same  age  as  the  Castine  formation." 

The  lode  follows  the  schistosity  of  the  country  rock,  striking  from 
N.  22°  E.  to  N.  70°  E.,  and  dips  from  45°  to  65°  N.  The  schist  is 
heavily  impregnated  with  sulphides  for  a  width  of  1  to  8  feet. 
Sheets  of  pure  sulphide  an  inch  or  two  wide  persist  for  several  feet 
along  the  dip  and  strike  and  are  overlapped  by  similar  sheets.  The 
rock  between  these  is  composed  of  innumerable  paper-thin  sheets  of 
alternating  sulphide  and  garnet. 

The  sulphides  are  steel-colored  zinc  blende,  pyrite,  galena,  and 
chalcopyrite.  Intergrown  intimately  with  them  is  a  considerable 
amount  of  magnetite.  The  gangue  minerals  are  garnet,  actinolite, 
sericite,  calcite,  chlorite,  quartz,  and  rhodochrosite ;  a  little  barite 
was  noted  on  the  dump.  Figure  7  is  a  sketch  of  a  thin  section  of  the 
ore,  showing  parallel  bands  of  garnet,  sericite,  and  sulphide.  With- 
out doubt  the  deposit  has  been  regionally  metamorphosed  since  it 
was  formed,  and  the  highly  schistose  structure  of  the  lode,  which 
parallels  that  of  the  country  rock,  has  resulted  from  the  same  dy- 
namic forces  that  developed  the  schistosity  in  the  country  rock.  Ac- 
cording to  George  H.  Holden  the  high-grade  ore  carries  zinc  30 
per  cent,  lead  16  per  cent,  silica  12  per  cent,  copper  2^  per  cent,  and 
gold  $2.50  a  ton.  The  minerals  with  the  exception  of  barite  and 
rhodochrosite  are  those  commonly  found  in  contact-metamorphic 
deposits,  but  they  have  been  crushed  or  redeposited  by  regional  meta- 
morphism. 

The  sulphides  have  been  crushed,  recemented,  and  in  part  re- 
crystallized.     The  chlorite  and  mica  seem  to  have  been  completely 

"Smith,  Bastin,  and  Brown,  folio  149,  Geol.  Atlas  U.  S.,  p.  5. 


38  SOME    ORE   DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 

dissolved  and  recrystallized  with  longer  axes  parallel  to  the  schis- 
tosity  and  to  the  orientation  of  the  lode.  The  garnet  is  so  highly 
fractured  that  in  places  it  is  almost  opaque  in  thin  section  when  the 
nicols  are  not  crossed.  None  of  the  garnet  shows  the  crystal  form. 
Garnet,  as  is  well  known,  is  formed  in  igneous  rocks,  in  contact -meta- 
morphic  deposits  in  some  deep  veins,  and  by  regional  metamorphism. 
In  igneous  rocks  it  is  nearly  always  idiomorphic.  In  contact-meta- 
morphic  deposits  it  is  either  massive  or  idiomorphic  and  very  often 
shows  such  optical  anomalies  as  double  refracting  rings.  It  may 
have  schistose  structure  when  it  replaces  schists,  but  it  is  not  highly 
fractured  like  the  Deer  Isle  garnets,  and  some  crystals  usually  have 
the  crystal  outline  or  else  show  the  double  refracting  rings.  In  the 
veins  of  the  deep  zone  it  is  usually  idiomorphic.  The  garnet  of  the 
Deer  Isle  mine  is  not  idiomorphic,  is  greatly  crushed,  and  does  not 
show  double  refracting  rings.  Under  the  microscope  it  has  the  color 
and  general  appearance  of  andradite  and  without  much  doubt  is  con- 
tact-metamorphic  garnet  which  has  been  regionally  metamorphosed 
by  pressure.     (See  fig.  7  and  PI.  I,  ^.) 

CAPE  ROZIER  MINE. 

The  Cape  Rozier  mine  is  at  Harborside,  across  the  harbor  from 
Castine.  The  country  rock  is  schistose  pyroclastic  tuff  of  the  Castine 
formation.  This  is  cut  by  diorite,  which  shows  no  schistosity. 
On  the  dump  are  fragments  of  the  Castine  formation  cut  by  thin 
sheets  of  pyrite  and  chalcopyrite  and  stained  with  green  copper  car- 
bonate. The  two  shafts  are  inaccessible.  Some  ore  on  the  dump  of 
upper  shaft  is  composed  of  calcite,  zinc  blende,  pyrite,  and  chalcopy- 
rite.    The  ore  observed  shows  no  schistosity. 

HERCULES   MINE. 

The  Hercules  mine  is  between  Penobscot  and  Castine,  just  above 
the  Bagaduce  Narrows.  A  shaft  sunk  at  tide  water  is  now  submerged. 
The  country  rock  is  the  Castine  formation,  which,  near  the  ore  body, 
is  highly  silicified  and  somewhat  sericitized.  Some  ore  on  the  dump 
shows  quartz,  sericite,  zinc  blende,  galena,  chalcopyrite,  pyrite,  pyr- 
rhotite,  and  specularite. 

JONES  &  DODGE   MINE, 

The  Jones  &  Dodge  mine  is  one-half  mile  southwest  of  the  Her- 
cules, on  the  south  shore  of  the  Bagaduce  Narrows.  The  country 
rock  is  the  pyroclastic  phase  of  the  Castine  formation,  which  at  the 
mine  shows  a  schistosity  striking  northward.  In  the  dark  biotitic 
portion  of  the  country  rock  certain  bands  carry  small  amounts  of 
pyrite,  chalcopyrite,  galena,  and  zinc  blende. 


HANCOCK    COUNTY. 


39 


EMERSON    MINE. 

The  Emerson  mine  is  near  the  Castine  ferry  on  the  west  shore  of 
Bagaduce  River.  A  two-compartment  shaft,  sunk  near  the  shore, 
is  under  water.  The  country  rock  shown  on  the  dump  is  devitrified 
rhyolite.  Some  of  this  is  brecciated  and  has  sulphide  ore  deposited 
between  its  fragments.  The  amount  of  ore  on  the  dump  is  very  small. 
The  minerals  noted  are  galena,  zinc  blende,  pyrite,  magnetite,  and 
pyrrhotite. 

SULLIVAN,    WAUKEAG,    AND    PINE    TREE    ]\riNES. 

At  West  Sullivan,  east  of  Frenchman  Bay,  several  mines  are  located 
along  tide  water.   These  include  the  Sullivan,  Waukeag,  and  Pine  Tree 


Granite 


Figure  12. — Cross  section  of  the  Sullivan  mine.      (After  Kempton.) 

mines,  all  of  which,  according  to  report,  are  on  the  same  lode.  The 
Sullivan  lode,  which  was  discovered  in  1877,  outcrops  below  high  tide. 
A  cofferdam  was  built  and  this  and  the  Waukeag  mines  were  worked 
from  1878  to  1884.  The  Waukeag,  which  operated  a  14-stamp  mill 
and  smelting  furnace,  is  reported  to  have  produced  25  tons  of  silver- 
lead  bullion.    All  the  mines  were  inaccessible  in  1909. 

The  country  rock  is  dark-gray  micaceous  schist,  probably  the 
Ellsworth.  Near  the  mines  the  schistosity  strikes  S.  75°  E.  and  is 
practically  vertical.  At  places  it  is  cut  by  a  dark  rock,  presumably 
a  diorite.  A  few  rods  west  of  the  Waukeag  shaft  are  large  outcrops 
of  medium-grained  granite,  composed  of  quartz,  feldspar,  biotite,  and 
muscovite.  The  Waukeag  shaft,  which  is  vertical,  is  reported  to  be 
410  feet  deep.  A  second  shaft  near  by  on  the  .same  property  is  60  feet 
deep.  On  the  Sullivan,  about  180  feet  southeast  of  the  Waukeag,  a 
shaft  is  driven  290  feet  on  a  steep  incline  to  the  northeast.  A  cross 
section  of  the  vein,  after  C.  W.  Kempton,  is  shown  in  figure  12.    The 


40  SOME    OEE   DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 

Milton  shaft,  about  one-fourth  mile  clown  the  bay  and  along  the  strike 
of  the  lode,  is  sunk  to  a  depth  reported  to  be  260  feet.  According  to 
report  the  lode  was  not  encountered  in  a  400-foot  crosscut  to  the 
southwest. 

To  judge  from  the  ore  on  the  dump  the  deposit  is  a  clean-cut  vein 
filling  a  fissure  in  the  schist  and  is  not  regionally  metamorphosed. 
The  gangue  is  quartz,  barite,  talc,  and  gypsum ;  the  sulphides,  which 
are  not  abundant  in  the  gangue,  include  zinc  blende,  galena,  pyrite, 
chalcopyrite,  arsenopyrite,  and  a  graj^  sulphide  which  is  probably  brit- 
tle silver.  Threads  of  native  silver  are  said  to  have  been  found  10  feet 
below  the  surface.  Magnetite,  specularite,  and  pyrrhotite  are  absent. 
The  quartz  is  usually  massive,  but  is  also  found  as  acicular  crystals 
pointing  to  the  center  of  a  druse.  Brecciated  fragments  of  the 
schistose  country  rock  are  included  in  the  ore  and  the  rounded  edges 
of  these  show  that  they  were  partly  dissolved  by  the  ore-depositing 
solutions.  These  relations  are  shown  in  figure  8.  The  schist  is  not 
strongly  leached  near  the  lode,  but  chlorite  and  sericite  have  devel- 
oped through  metasomatic  processes. 

The  banded  ore  is  not  schistose  like  the  pyritic  copper  ores  in  the 
Ellsworth  schist  and  is  clearly  of  later  age ;  it  was  probably  formed 
at  the  time  of  the  intrusion  of  the  granite. 

C.  W.  Kempton,"  who  was  engaged  as  a  mining  engineer  at  Sulli- 
van in  1877,  gives  the  following  information  relating  to  the  Sullivan 
mine : 

Proceeding  witb  the  shaft,  at  about  30  feet  deptli,  the  vein,  composed  of 
quartz,  with  more  or  less  slate  highly  imi)regnated  with  sulphides,  was  found 
to  be  4  feet  wide.  *  *  *  The  ore  is  essentially  silver,  sulphides  and  native, 
in  quartz  and  slaty  gangues,  with  slight  amounts  of  iron,  zinc,  etc.,  as  sul- 
phides, and  also  galena.  Of  the  silver  minerals,  stromeyerite  is  most  plentiful, 
stephanite  next,  argentite  (silver  glance),  common,  native  silver  in  flakes  very 
plenty,  threads  frequent,  lumps  occasional. 

Kub.v  silver  is  exceedingly  rare;  antimonial  silver  has  been  found.  The 
occasional  yellow  copper  sulphide  met  with  has  a  peculiar  luster  and  runs 
very  rich  in  silver. 

As  stated  above,  the  course  of  the  vein  is  from  northwest  to  southeast,  with 
the  strike  of  the  slate  running  parallel  to  the  line  of  contact  of  the  granite. 
The  vein  is  in  the  slate,  dipping  at  an  angle  of  70°  from  the  horizon,  north- 
easterly, toward  the  granite,  which  it  probably  reaches  in  less  than  a  thousand 
feet.  The  slate  also  dips  toward  the  granite  at  this  place  about  37°  from 
horizontal,  although  at  some  other  places  not  more  than  12°. 

At  the  contact  of  the  slate  and  granite  the  latter  often  penetrates  the  bed- 
ding of  the  slate,  in  known  instances  nearly  200  feet.  The  granite  is  much 
cut  up  by  dikes  of  black  trap,  which  also  runs  into  the  slate,  faulting  the  vein 
in  several  ))l;ices.- 

GOULDSBOROUGH    MINE. 

The  Gouldsborough  mine  is  in  the  town  of  Gouldsborough,  about 
9  miles  southeast  of  West  Sullivan.     A  shaft  150  feet  deep  is  sunk  on 

"Trans.  Am.  Inst.  Min.  Eng.,  vol.  7.  1S78,  p.  349. 


HANCOCK   COUNTY.  41 

the  lode  and  a  drift  is  driven  nortljweslward  75  feet  from  the  100-foot 
level.  The  mine  is  now  under  water.  On  the  surface  the  vein  is 
stoped,  underhand,  in  an  open  cut  150  feet  long,  which  reaches  a 
maximum  depth  of  about  50  feet.  In  the  early  eighties  some  ore  was 
shipped.  The  countr}^  rock  is  dark  quartz  diorite,  which  shows  no 
sign  of  contortion  or  regional  metamorphism.  One  mile  to  the  south 
there  are  large  areas  of  granite  and  near  the  mine  the  brecciated 
diorite  is  cut  by  granite  veinlets.  Near  the  lode  the  diorite  is 
somewhat  decomposed  and  locally  it  is  brecciated  and  cemented  by 
rhodochrosite. 

The  lode  is  a  fissure  vein  which  strikes  N.  63°  E,  and  is  approxi- 
mately vertical.  It  varies  in  width  from  6  inches  to  2  feet  and  is 
composed  of  banded  quartz  and  sulphides,  with  angular  slabs  of 
country  rock.  The  metalliferous  minerals  are  galena,  chalcopyrite, 
pyrite,  zinc  blende,  and  a  very  small  amount  of  magnetite.  The  pro- 
portion of  sulphide  to  quartz  is  high  and  the  ore  is  said  to  carry 
considerable  silver.  The  hydrothermal  metamorj)hism  of  the  wall 
rock  is  clearly  shown.  The  quartz  diorite  is  a  medium-grained  rock, 
is  very  fresh,  and  is  composed  of  oligoclase,  andesine,  hornblende, 
biotite,  quartz,  orthoclase,  and  pyrite.  Within  a  few  feet  of  the  lode 
this  is  altered  to  a  rock  composed  of  chlorite,  sericite,  epidote,  quartz, 
and  pyrite.  The  chloritization  does  not  extend  far  from  the  lode.  A 
rod  or  two  away  a  brecciated  quartz  diorite  is,  as  already  stated,  ce- 
mented by  coarse  granite.  The  quartz  diorite  is  certain!}^  older  than 
the  granite,  and  the  granite  is  probably  the  source  of  the  ores. 

The  outcrop  is  partly  oxidized,  but  sulphides  appear  within  a  few 
feet  of  the  surface.  The  banding  of  the  ore,  the  open  druses  parallel 
to  bands,  the  brecciation  of  diorite  and  its  inclosure  in  ore,  the  absence 
of  crenulation  and  foliation  in  the  vein,  and  the  characteristic  hydro- 
thermal  metamorphism  of  the  wall  rock  show  that  the  deposit  belongs 
to  the  class  which  postdates  regional  metamorphism. 

FRANKLIN    EXTENSION    MINE. 

The  Franklin  Extension  mine  is  2  miles  west  of  Franklin  station 
and  one-eighth  mile  west  of  West  Franklin.  The  lode  is  a  narrow 
fissure  vein  in  contorted  schist,  presumably  the  Ellsworth.  It  strikes 
]Sr.  18°  E.  and  is  approximately  vertical.  Two  shafts,  said  to  be  on 
the  same  lode,  are  sunk  about  300  feet  apart.  The  ore  is  composed  of 
quartz,  arsenopyrite,  galena,  and  pyrite.  Granite,  cutting  the  Ells- 
worth schist,  is  exposed  within  a  few  feet  of  the  lode.  The  deposit, 
which  is  said  to  carry  silver,  is  banded  and  shows  comb  structure.  It 
is  clearly  of  later  age  than  the  metamorphism  of  the  schist. 

COPPEROPOLIS    MINE. 

The  Copperopolis  mine  is  near  Egypt,  4  miles  west  of  Franklin 
station.     Two  hundred  yards  west  of  the  mine  house  three  pits  are 


42  SOME    ORE    DEPOSITS    IN    MAINE   AND    NEW    HAMPSHIRE. 

sunk  in  the  contorted  Ellsworth  schist,  which  carries  seams  of  quartz 
and  pyrite  with  stains  of  copper  carbonate.  The  Harvey  Elliott 
prospect  is  about  300  yards  east  of  the  mine  house.  The  shaft  was 
under  water  Avhen  visited,  but  to  judge  from  the  dump  the  country 
rock  is  the  Ellsworth  schist  intruded  by  a  dark  igneous  rock  which  is 
slightly  schistose.  The  ore  consists  of  thin  sheets  of  quartz,  calcite, 
rhodochrosite,  j^yrite,  and  chalcopyrite. 

CATHERINE    HILL    MOLYBDENUM    MINE. 

The  Catherine  Hill  molybdenum  mine  is  at  the  north  end  of  Tunk 
Pond,  near  the  summit  of  Catherine  Hill.  The  deposit  was  described 
by  F.  L.  Hess  «  in  1908. 

The  country  rock  is  a  medium-grained  granite  composed  of  ]Dink 
and  white  feldspar  (orthoclase  and  albite),  quartz,  biotite,  and  mus- 
covite.  The  granite  is  cut  by  aplite  dikes  from  one-half  inch  to  4 
inches  wide,  some  of  which  dip  about  15°  N.  It  is  cut  also  by  numer- 
ous pegmatite  veins  and  veinlets  which  vary  from  coarse  to  fine  peg- 
matite, the  minerals  of  the  latter  being  only  a  little  larger  than  the 
crystals  of  the  granite.  The  deposits  are  worked  by  open  cuts  on  a 
ledge  of  granite  which  trends  eastward.  The  principal  opening  is  75 
feet  long  and  15  feet  wide  and  has  a  maximum  depth  of  "20  feet.  The 
pegmatite  veins  carry  quartz,  feldspar,  molybdenite,  apatite,  biotite, 
chlorite,  hornblende,  and  fiuorite.  At  some  places  quartz  and  feld- 
spar are  graphically  intergrown.  Miarolitic  cavities  are  found  in 
both  the  granite  and  the  pegmatite,  and  in  the  latter  are  lined  with 
quartz  crystals.  The  molybdenite  occurs  as  scales  and  flakes  from 
one-eighth  inch  to  1  inch  in  diameter;  some  of  them  are  in  cracks 
which  join  the  pegmatite  veins,  others  in  the  pegmatite  veins  them- 
selves, and  still  others  in  the  granite  in  positions  which  seem  to 
have  no  connection  with  the  pegmatite  veins.  Most  of  the  molyb- 
denite is  in  or  within  a  few  inches  of  the  pegmatite,  yet  some  of  it 
seems  to  be  an  original  constituent  of  the  granite.  There  is  little  or 
no  sericitization  in  the  granite  that  carries  molybdenite,  and  under  the 
microscope  the  molybdenite  is  seen  to  inclose  well-shaped  crystals  of 
albite  and  orthoclase,  the  corners  of  which  are  slightly  rounded,  indi- 
cating that  the  potash  and  soda  feldspars  were  floated  in  the  molyb- 
denum sulphide  solution  and  were  partly  dissolved  before  it  solidi- 
fied. The  structure  is  much  the  same  as  that  shown  by  some  dia- 
bases where  augite  incloses  idiomorphic  feldspar,  except  that  the 
corners  of  the  feldspars  in  the  ore  have  been  rounded  by  corrasion.  A 
photomicrograph  of  this  ore  is  shown  in  Plate  III,  B. 

"Bull.  U.  S.  Geol.  Survey  No.  340,  1908,  pp.  2.34-235. 


U.    S.    GEOLOGICAL  SURVEY 


BULLETIN  432       PLATE    III 


A.     POLISHED  SURFACE  OF  SCHISTOSE  ORE  OF  MILAN   MINE. 


B.     PHOTOMICROGRAPH   OF   MOLYBDENITE  ORE  FROM   CATHERINE  HILL. 


WASHINGTON    COUNTY.  43 

WASHINGTON   COUNTY. 
GENERAL  STATEMENT. 

The  geology  of  a  portion  of  Washington  County  has  been  described 
by  George  Otis  Smith  and  David  White."  The  eastern  part  of  the 
county  has  been  mapped  by  E.  S.  Bastin  and  will  be  described  in  a 
folio  of  the  Geologic  Atlas  of  the  United  States  soon  to  be 
published.  The  western  part  of  the  county  is  made  up  in  the 
main  of  slates  and  argillaceous  schists.  The  zinc  lode  of  Cherryfield 
is  inclosed  in  these  rocks,  but  so  far  as  known  there  are  no  schistose 
deposits  of  pyritic  copper  ores  in  Washington  County.  East  of  this 
area  of  slates  and  schists  is  a  broad  belt  of  intruding  granite  which 
extends  from  JonesjDort  to  Calais.  Some  deposits  of  molybdenite 
described  by  F.  L.  Hess  ^  are  associated  with  pegmatitic  phases  of  the 
granite.  East  of  this  broad  belt  of  granite,  and  including  Pembroke, 
Lubec,  and  Eastport,  is  a  large  area  of  rhyolite,  trap,  and  other  vol- 
canic rocks  which  are  in  part  later  than  the  granite.  The  Lubec 
lead  mine,  the  Denbow  Point  silver  deposit,  and  the  copper  deposits 
in  Pembroke  are  associated  with  the  basic  phases  of  these  volcanic 
rocks. 

CHERRYFIELD    MINE. 

The  Cherryfield  mine,  one-half  mile  east  of  Cherryfield,  was  first 
opened  in  1878  and  reopened  in  1905.  In  1909  it  was  under  water. 
G.  O.  Smith  visited  the  mine  in  1907,  and  the  following  description 
is  taken  chiefly  from  his  notes.  The  country  rock  is  a  dark  aphanitic 
diabase,  without  conspicuous  phenocrysts,  and  is  composed  of  horn- 
blende, feldspar,  quartz,  and  magnetite;  under  the  microscope  it  is 
seen  to  have  a  well-defined  schistosity.  Near  the  mine  the  dark  schist 
is  cut  by  unsheared  cliorite,  and  granite  outcrops  about  three-fourths 
mile  to  the  northwest.  The  deposit  is  a  fissure  vein  which  cuts  the  dia- 
base, strikes  N.  85°  W.,  and  dips  steeply  northward.  A  two-compart- 
ment shaft  is  sunk  on  the  lode  to  a  depth  of  260  feet,  and  three  short 
drifts  are  turned  from  this  shaft.  The  vein  is  from  12  to  20  inches 
wide,  is  banded,  and  contains  fragments  of  the  country  rock.  The 
minerals  are  quartz,  calcite,  zinc  blende,  galena,  pyrite,  and  chalcopy- 
rite,  and  the  ore  is  said  to  carry  silver  values.  Chlorite  is  developed  in 
the  wall  rock  near  the  lode,  but  sericite  is  not  conspicuous.  No  schis- 
tose ore  was  noted  on  the  dump.  A  mill,  erected  in  1907,  is  equipped 
with  crusher,  rolls,  trommel,  jigs,  and  concentrating  table.  A  high 
percentage  of  the  selected  ore  is  zinc  blende. 

<■  Geology  of  the  Perry  Basin  :  Prof.  Paper  U.  S.  Geol.  Survey  No.  35,  1905. 
"  Bull.  U.  S.  Geol.  Survey  No.  340,  1908,  pp.  231-234. 


44 


SOME    ORE    DEPOSITS   IN    MAINE    AND    NEW    HAMPSHIRE. 


LUBEC    LEAD    MINE. 

The  Lubec  mine  is  located  about  7  miles  by  wagon  road  from  Lubec, 
on  a  shore  marked  by  high,  steep  cliffs  along  which  the  veins  outcrop. 
According  to  report  the  deposit  avp.s  discovered  in  1828  and  has  been 
worked  in  a  small  way  through  several  short  periods.  A  mill,  now  in 
ruins,  is  said  to  have  been  in  operation  for  about  six  years  in  the  late 
sixties  and  early  seventies.  A  report  on  the  mine  by  N.  S.  Manross  is 
included  in  the  report  upon  the  natural  history  and  geology  of 
Maine  for  1861  (p.  299).  xVt  present  the  mine  is  idle  and  the 
deep  workings  are  submerged.     A  mill  built  in  late  years  is  equipped 


50  Feet 


FiGORE  13. — Sketch  showing  position  of  pi'incipal  veins  in  Lubec  lead  mine. 

with  jaw  crusher,  coarse  and  fine  rolls,  screens,  jigs,  a  Wilfley  table, 
and  two  Frue  vanners.  Steam  power  was  used  and  the  milling  was 
done  with  salt  water. 

The  country  rock  is  a  dense  green  trap — an  altered  surface  lava. 
Near  the  mill  the  trap  is  in  faulted  contact  with  a  dark  fissile  shale. 
The  freshest  specimens  of  the  trap  contain  much  secondary  calcite, 
chlorite,  and  a  little  white  mica.  Near  the  lode  and  in  the  fragments 
which  the  ore  includes  chlorite  appears  to  be  more  abundant  than  else- 
where, but  sericite  is  not  consjncuously  developed. 


WASHINGTON    COUNTY. 


45 


The  depOvSits  are  closely  spaced  intersecting  fissure  veins,  some  of 
which  are  shown  in  figure  13.  The  ore  carries,  besides  lead  and  zinc, 
some  silver,  a  little  copper,  and  a  trace  of  gold.  The  minerals  are 
quartz,  calcite,  galena,  zinc  blende,  pyrite,  chalcopyrite,  and  limonite 
and  manganese  oxides.  At  many  places  the  lodes  are  opened  by  short 
tunnels,  deep  cuts,  and  underhand  stopes.  Below  the  mill  a  shaft 
is  sunk  on  the  principal  lode,  but  in  1909  this  was  under  water. 
Above  the  mill  this  vein  (No.  8),  which  strikes  westward,  is  well 
exposed  in  the  open  cut,  and  considerable  ore  has  been  removed.  It 
is  a  foot  or  more  wide  and  carries  galena.  It  consists  of  a  number  of 
thin,  closely  spaced,  anastomosing  fissures,  between  which  are  broken 
fragments  of  trap.  Some  of  the  stringers  of  galena  play  out 
as  they  pass  into  the  country  rock.  The  shaft  sunk  on  this  vein  is 
reported  to  be  180  feet  deep,  and  drifts  are  run  out  170  feet  under 
the  bay.  Vein  No.  9  is  east  of  No.  8,  strikes  N.  50°  W.,  and  would 
intersect  No.  8  below 
the  bay.  Not  far  from 
the  shore  a  50-foot  tun- 
nel is  driven  in  this  de- 
posit. Where  exposed 
along  the  cliff  the  vein 
is  a  breccia  zone  10 
feet  wide,  with  about 
10  per  cent  of  ore  and 
g  a  n  g  u  e  minerals  in 
broken  country  rock. 
No.  5  vein,  which 
strikes  a  few  degrees 
east  of  north,  crosses 
the  other  lodes,  and  for 
80  feet  along  its  strike  forms  a  cliff  escarpment  30  feet  high.  Along 
its  face  are  thin  flakes  of  sulphide  ere.  As  shown  by  this  vein,  both 
sets  of  fractures,  which  are  nearly  at  right  angles  to  each  other,  were 
formed  before  mineralization.  This  is  illustrated  also  in  a  small 
vein  (No.  2)  of  quartz  and  galena,  which  strikes  northeastward  and 
ends  in  a  crossing  fissure  in  a  small  pit  northeast  of  the  mine.  The 
galena  and  quartz  follow  the  fissure  for  a  few  inches,  making  a  large 
angle  with  their  former  course,  as  is  indicated  in  figure  14. 

There  are  said  to  be  thirteen  veins  in  all,  but  some  of  those  exposed 
at  tide  water  to  the  south  of  the  mill  are  very  small. 

DENBOW  POINT  MINE. 

On  Denbow  Point  a  shaft  is  sunk  in  basic  tuffs,  but  has  been  lost 
through  caving.  The  country  rock  thrown  up  on  the  dum^D  shows 
stringers  of  ore  composed  of  quartz,  zinc  blende,  galena,  and  pyrite. 


5  Feet 


Figure  14. — Sniall  vein  in  Lubec  lead  mine.     Thie  vein 
is  later  than  the  fissure  in  wliicli  it  ends. 


46 


SOME    OEE   DEPOSITS   IN    MAINE    AND    NEW    HAMPSHIEE. 


PKOSPECTS    IN    PEMBROKE. 

On  the  road  from  West  Pembroke  to  Ayres  Junction,  about  2  miles 
northwest  of  West  Pembroke^  there  are  several  prospects  in  diabasic 
lavas.  The  most  extensive  workings  are  on  the  Sinclair  farm,  where 
the  Eastern  Exploration  Company  has  recently  been  prospecting. 
The  workings  are  all  open  cuts  from  5  to  15  feet  deep,  and  some  of 
these  are  extensive.  (See  fig.  15.)  The  country  rock  is  vesicular  trap 
which,  except  for  a  little  shearing  at  pit  No.  5,  shows  no  meta- 
morphism.  The  ore  occurs  as  veinlets  filling  fractured  zones,  as  dis- 
seminations in  vesicular  lava,  and  as  amygdaloidal  fillings  in  the  lava. 

There  is  some  chlo- 
ritization,  but  seri- 
citization  is  not  ex- 
tensive. The  min- 
erals present  are 
sphalerite,  chalco- 
pyrite,  pyrite,  ga- 
lena, arsenop7/rite, 
and  bornite,  with  a 
little  limonite  near 
the  surface  and 
some  small  stains 
of  malachite.  The 
gangue  is  dolomite, 
calcite,  and  quartz, 
and  at  some  places 
there  is  a  noticeable 
amount  of  cherty 
silica.  The  dolo- 
mite, which  is  the 
most  abundant  min- 
eral associated  with 
the  ore,  is  jjresuma- 
bly  ferruginous,  since  it  is  nearly  everywhere  stained  with  a  brown 
film  upon  the  weathered  surface. 

At  pit  No.  5,  which  is  120  yards  northwest  of  the  blacksmith  shop, 
an  excavation  about  20  by  J:0  feet,  sunk  to  a  maximum  depth  of  about 
10  feet,  has  been  made  on  a  glaciated  surface.  The  rock  here  is  a 
bluish-gray  amygdaloid,  bleached  white  near  the  surface.  Bands  of 
dense  gray  flows  alternate  with  the  vesicular  phases,  the  banding  of 
the  rock  striking  about  southwest.  The  flows  are  cut  by  closely  spaced 
parallel  fractures  which  are  nearly  vertical  and  strike  S.  55°  W. 
There  is  a  little  shearing  along  some  of  these  fissures  as  if  they  had 
resulted   from  compressive  stresses.     The  amygdaloids  are  from  one- 


300  Feet 


Figure  15. — Sketch  showing  position  of  pits  of  Eastern  Ex- 
ploration Company  at  Pembroke.     By  E.  S.  Bastin. 


WASHINGTON    COUNTY.  47 

eighth  to  one-half  inch  in  diiimeter,  and  many  are  filled  with  pure 
white  calcite,  others  are  filled  with  calcite  and  quartz,  and  some  of 
them  are  lined  with  shells  of  metallic  sulphides  with  ciystalline 
quartz  inside.  Some  of  the  ore  is  in  the  sheared  fractures  and  some 
is  disseminated  in  the  rock  near  the  fractures.  Most  of  the  sulphides 
appear  as  small  bodies  not  one-half  inch  in  diameter,  but  some  are  in 
masses  measuring  4  to  5  inches;  zinc  blende  predominates.  Fifty 
yards  northwest  of  this  pit  a  small  cut  shows  banded  comb  quartz 
with  zinc  blende  and  galena. 

At  pit  No.  2  the  trap  is  traversed  by  small  irregular  fractures 
healed  with  quartz  and  sulphides.  The  relations  are  shown  in  fig- 
ure 15.  At  pit  No.  4,  200  yards  southwest  of  the  blacksmith  shop,  the 
country  rock  is  darker  than  at  pit  No.  5  and  some  is  porphyritic,  but 
it  is  presumably  a  part  of  the  same  flow.  The  rock  is  cut  by  many 
thin  stringers  of  metallic  sulphides,  galena  and  chalcopyrite  being- 
more  abundant  than  at  other  pits.  This  pit  is  125  feet  long  and  20 
feet  wide ;  its  trend  is  S.  30°  E.,  and  most  of  the  small  stringers  strike 
southwestward  across  it. 

COOPER  MINE. 

Molybdenum  deposits  have  been  opened  at  Cooper,  and  the  Amer- 
ican Molybdenum  Company  has  erected  a  mill  there  for  treating  the 
ore.  The  deposits  have  been  described  by  George  Otis  Smith®  and 
the  following  notes  are  abstracted  from  his  report : 

The  country  rock  is  granite,  presumably  of  late  Paleozoic  age,  and 
is  cut  by  pegmatite  dikes.  In  and  near  the  dikes  bunches  of  molyb- 
denite crystals  1  to  2  inches  in  diameter  are  intimately  mixed  or  inter- 
grown  with  the  quartz  and  feldspar  of  the  pegmatite,  w'here  they 
were  deposited  by  the  pegmatite  magma.  They  also  occur  in  flakes 
and  nests  disseminated  through  the  granite  mass,  especially  near 
the  pegmatite,  where  they  may  have  consolidated  from  the  granitic 
magma  or  may  have  been  brought  in  by  the  pegmatite  solutions, 
which  are  regarded  as  nearly  contemporaneous  with  the  granitic 
intrusion.  The  deposits  were  visited  by  F.  L.  Hess,^  wdio  reports 
that  the  molybdenite-bearing  granite  in  the  American  Molybdenum 
Company's  mine  is  shown  by  a  trench  and  crosscut  to  be  at  least  300 
feet  long  and  100  feet  wide.  Mr.  Hess  also  reports  that  the  Calais 
Molybdenite  Mining  Company,  whose  property  joins  the  American 
Molybdenum  Companj^'s  holdings  on  the  north,  has  opened  up  similar 
deposits.  Molybdenite  has  also  been  found  near  Sand  Cove,  Tunk 
Pond,  and  in  the  town  of  Brunswick,  Cumberland  County — at  both 
places  in  the  granite. 

"Bull.  U.  S.  Geol.  Survey  No.  260,   1905,  p.  17. 

"  Molybdenite  in  Maine,  Utah,  and  California  :  Bull.  U.  S.  Geol.  Survey  No.  340,  1908, 
p.  231. 


48 


SOME    ORE    DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 


SOMERSET   AND   OXEORD   COUNTIES. 
ROBINSON    MINE. 

The  Robinson  mine,  in  Concord  Township,  Somerset  County,  7 
miles  southwest  of  Bingham  and  about  1^  miles  north  of  Em  den 
Pond,  was  discovered  by  W.  S.  Robinson  in  1898  and  has  been  worked 
noAv  and  then  for  several  years.  It  is  now  owned  by  the  Somerset 
Mining  Company,  which  has  erected  a  concentrator  near  the  mine. 


Section  along  Wne  ji-A 


Limestone 


faiJit 


A 


Limestone  han^inj^  wai 
7S' 


\    Quartzite 
hanging  wall 


2-Foot  ore.      ^    ^  3-foot  or 


X 


30  Feet 


FiGUEB  16. — Plan  and  cross  section  of  the  Robinson  mine,  near  Concord,  Somerset  County. 

This  mil]  is  equipped  with  a  12-inch  Blake  crusher,  a  set  of  rolls,  a 
trommel,  and  three  jigs.  It  employs  steam  power  generated  by  wood 
and  has  a  capacity  of  10  tSns  daily.  A  small  amount  of  concentrates 
and  8  carloads  of  ore  have  been  shipped.  The  property  has  been  idle 
since  1907. 


SOMERSET   AND   OXFORD   COUNTIES. 


49 


The  country  is  an  area  of  quartzite,  limestone,  and  shales,  which 
are  somewhat  metamorphosed.  These  rocks  are  cut  by  trap  dikes 
and  probably  by  other  intrusives.  The  quartzite  consists  of  rounded 
quartz  grains  which  under  the  microscope  are  seen  to  be  rimmed  Avith 
secondary  silica.  Between  these  grains  biotite,  chlorite,  and  horn- 
blende have  developed.  As  shown  in  figure  16,  the  deposit  is  a 
bedding-plane  fissure  which  occupies  the  axis  of  an  anticlinal  fold. 
In  thickness  it  varies  from  2  to  8  feet  and  is  thickest  at  the  crest  of 
the  anticline,  where  it  has  been  stoped  or  quarried  out  for  about  GO 
feet  along  the  strike  of  the  crest  and  from  10  to  25  feet  across  it.  At 
the  southwest  end  of  the  open  cut  a  fault  strikes  N.  50°  W.  and  dips 
75°  SW.  South  of  this  fault  the  hanging  wall  of  the  deposit  is  sandy 
limestone  overlain  by  shale;  northeast  of  the  fault  it  is  quartzite. 
The  fault  is  clearly  older  than 
the  lode,  for  the  lode  crosses 
it  without  interruption.  (See 
fig.  17.)  A  trap  dike  6  inches 
wide,  encountered  on  the  south- 
west end  of  the  cut,  is  followed 
in  a  tunnel  some  15  feet.  This 
dike  rock  is  a  very  fresh  basalt ; 
even  its  olivines  are  but  slightly 
altered,  and  it  is  clearly  later 
than  the  ore  body  which  it 
crosses. 

The  gangue  consists  of  quartz 
and  dolomite.  The  metallic 
minerals  are  pyrite,  galena, 
zinc  blende,  chalcopyrite,  ar- 
senopyrite,  pyrrhotite,  and  a 
little  bornite.  The  sulphides  are  said  to  carry  silver.  Much  of  the 
lode  is  barren  white  quartz,  and  the  sulphides  in  the  run  of  mine  do 
not  constitute  more  than  4  per  cent  of  the  mass,  though  in  selected 
ore  they  run  higher.  The  lode  near  the  dike  is  quartz,  with  no  me- 
tallic minerals.  Just  at  the  contact  it  is  slightly  oxidized  and  any 
metamorphic  changes  would  be  obscured,  but  an  inch  away  it  has 
sufl'ered  no  visible  change  at  the  contact  with  the  trap. 

MOUNT  GLINES. 

The  deposits  at  Mount  Glines,  in  Oxford  County,  have  been  de- 
scribed in  a  paper  by  George  Otis  Smith,"  from  which  are  extracted 
the  folloAving  notes : 

At  Milton  plantation  there  are  quartz  veins  in  a  gneissoid  granite 
which  is  probably  older  than  the  granite  quarried  on  the  Maine  coast. 
The  principal  lode  is  a  well-defined  fissure  vein,  with  a  maximum 
width  of  4^  feet,  composed  of  quartz  and  wall  rock,  the  latter  altered 

<•  Bull.  U.  S.  Geol.  Survey  No.  225,  1904,  p.  81, 
42381°— Bull.  432—10 i 


25  Feet 


Figure  17. — Vertical  section  of  wall  at  open 
cut,  Robinson  mine,  near  Concord,  Somerset 
County.  Faulting  is  older  than  ore  deposi- 
tion, o.  Shale  ;  h,  limestone  ;  c,  quartzite  ; 
d,  quartz  and  ore. 


50  SOME    OEE   DEPOSITS    IN    MAINE   AND    NEW    HAMPSHIEE. 

to  kaolin  and  sericite.  The  ore  minerals  are  pyrite  and  galena,  which 
occur  in  bunches  and  bands  up  to  4  inches  wide.  The  sulphide  ores 
cross  the  structure  of  the  quartz  gangue  and  are  presumably  of  later 
origin  than  the  major  portion  of  the  quartz.  Assays  made  by  the 
Mount  Glines  Gold  and  Silver  Mining  Company  are  said  to  give  good 
value  in  silver,  copper,  and  lead,  but  these  are  presumably  of  picked 
specimens.  A  sample  taken  from  the  upper  joortion  of  the  35-foot 
shaft,  where  the  vein  is  2|  feet  wide,  and  assayed  by  Dr.  E.  T.  Allen, 
yielded  less  than  $1  in  combined  metals. 

MILAN  MINE,   NEW  HAMPSHIRE. 
GENERAL  STATEMENT. 

The  Milan  mine  is  in  Coos  County,  northern  New  Hampshire,  in 
the  foothills  of  the  Presidential  Range,  about  8  miles  northwest  of 
Berlin  and  one-fourth  mile  from  the  Grand  Trunk  Railway  at 
Marston,  with  which  it  is  connected  by  tramway.  The  deposit  was 
discovered  in  the  seventies  and  was  worked  steadily  until  1886. 
According  to  Herbert  J.  Davis,"  the  monthly  production  was  2,600 
tons,  and  this  production  was  presumably  sustained  for  several  years. 
A  60-ton  smelter  was  installed  at  the  mine,  but  the  fumes  killed  the 
spruce,  and,  owing  to  objections  of  the  farmers  and  the  decline  in  the 
price  of  copper,  this  was  closed  after  a  small  tonnage  had  been  -put 
through.  The  jDroperty  was  opened  again  in  1895,  when  lessees 
mined  about  1,500  tons  of  ore.  It  was  acquired  in  1907  by  J.  B, 
Carper,  of  Portland,  who  organized  the  Milan  Mining  and  Milling 
Company,  which  is  now  working  the  mine  and  making  regular  ship- 
ments of  ore  and  concentrates. 

The  deposit,  first  worked  by  open  cuts,  is  operated  through  a 
265-foot  shaft  inclined  from  59°  to  85°  W.  Levels  are  turned  70, 
88,  115,  and  215  feet  (measured  on  the  incline)  below  the  collar;  these 
aggregate  about  1,500  feet. 

The  character  of  the  deposit  and  its  situation  and  accessibility  to 
markets  for  all  the  products  favor  low  costs  both  for  mining  and 
for  milling.  The  stojoes  are  at  many  jDlaces  from  10  to  20  feet  wide 
and  the  rock  breaks  well  and  runs  easily  in  the  chutes.  Practically 
no  timbering  is  required  to  hold  the  ground  even  when  the  large 
stopes  are  left  open.  The  concentration  of  the  ore  is  satisfactory 
for  the  pyrite,  but  the  saving  of  copper,  gold,  and  silver  is  low,  and 
where  these  exceed  a  certain  value  it  is  found  to  be  more  profitable 
to  ship  the  rock  than  to  mill  it.  The  ore  is  mined  with  air  drills, 
dumped  in  a  chute,  and  loaded  in  buckets  of  1,200-pound  capacity. 
It  is  hoisted  to  the  top  of  the  mill,  where  it  falls  over  a  grizzly,  the 
fines  going  to  a  1-inch  shaking  screen,  from  which  they  go  over  an 
elevator  to  the  rolls.  The  coarse  rock  from  this  screen  and  from 
the  grizzly  passes  over  two  picking  belts  on  which  the  ore  is  washed 

"Mineral  Ucsoui-ces  U.  S.  for  1885,  U.  S.  Geol.  Survey,  1886,  p.  501. 


MILAN    MINE,    NEW    ITAMPSIIIEE. 


51 


by  a  small  stream  of  water  to  facilitate  cobbing.  The  waste  from  the 
picking-  belt  is  sent  to  the  clump,  the  low-grade  pyrite  ore  is  run 
through  the  mill,  and  the  ore  carrying  a  noticeable  amount  of  copper 
is  shipped  to  smelters.  The  milling  ore  goes  through  a  Dodge  crusher 
and  is  elevated  to  the 

Grizzly 


ore  bin,  from  which  it 
passes  through  coarse 
rolls,  up  an  elevator 
through  an  impact 
screen  of  one-eighth 
inch  mesh.  From  this 
screen  the  fines  go  to 
a  thickening  tank  and 
pass  to  a  Richards  pul- 
sator  classifier,  where 
they  are  classified  for 
the  two  Wilfley  and 
three  Bartlett  tables. 
The  coarse  material 
from  the  screen  goes 
through  fine  crushing 
rolls  and  is  elevated 
back  to  the  shaking 
screen.  The  mill  feed 
carries  about  26.5  per 
cent  sulphur  and  1.35 
per  cent  copper.  The 
concentration   is   2   or 


Fine 
I 
1-inch  screen 


Coarse 

f 

Picking  belt 


Fine 


Coarse 
I 
Picking  belt 


Shipping  ore 


Waste 


Shipping 
ore 


Milling  ore 

Dodge  crusher 

1 

Elevator 

I 

Bin 

t 

Coarse  rolls 


Elevator 


Undersize 

Thickening  tank 
t 
Richards  pulsating  classifier 

2  Wilfley  and  3  Bartlett  tables 


Impact  screen  Vs  in. 

— '  ^     f  . 

Oversize 

Fine  rolls 

i 


Concentrate  to 
bins 


to  sluice 


FiGDEH  18. — Plan  of  ore  treatment  at  Milan  mine, 
New  Hampshire. 


3  to  1  and  the  concentrates  are  shipped  to  acid  works,  from  which 
the  cinders  are  sold  to  smelters  and  smelted  for  the  copper,  gold, 
and  silver.  Analyses  of  representative  concentrates  and  cobbed  ores 
are  given  below : 

Analysis  of  concentrates  from  Milan  mine. 

[Chas.  L.  Constant,  analyst.] 

Ounces  per  ton. 

Gold 0.  21, 

Silver 1.  50 

Per  cent. 

Copper 1.  58 

Arsenic None. 

Sulphur 41.30 

Silica 12.  47 

Alumina 2.80 

Iron 35.00 

Lime Trace. 

Magnesia  0.30 

Zinc 6.46 


52  SOME    OKE   DEPOSITS   IN    MAINE    AND  "NEW    HAMPSHIEE. 

Analysis  of  shipping  ore  cothed  from  the  mine  run. 

Per  cent. 

Insoluble- 15.40 

Sulphur 39.  84 

Copper 2.  25 

Zinc ^ 7.26 

Lead   1.57 

Iron 32.85 

The  ore  carries  about  $1.50  in  gold  and  1  or  2  ounces  in  silver  to  the 
ton,  and  the  sulphur,  iron,  copper,  gold,  and  silver  yield  from  $12  to 
$18  a  ton.  There  is  a  considerable  accumulation  of  tailings  from  for- 
mer operations  which  carry  36  per  cent  of  sulphur  and  1  per  cent  of 
copper,  and  these  are  now  being  put  through  the  mill  for  their  pyrite 
content.  From  the  low  copper  content  of  the  concentrates  it  appears 
that  a  high  percentage  of  the  copper  passes  off  in  the  slimes. 

GEOLOGY. 

The  Milan  area  is  included  in  the  great  shield  of  crystalline  schists 
which  covers  most  of  New  England  and  which  is  generally  regarded 
as  of  pre-Cambrian  age.  These  schists  have  been  intruded  presum- 
ably in  Paleozoic  time  by  great  masses  of  granitic  rocks  which  show 
little  or  no  deformation  by  shearing  and  are  therefore  later  than  the 
regional  metamorphism  of  the  schists.  To  the  east  and  south  these 
rocks  cover  extensive  areas,  but  they  are  not  known  to  be  present 
in  the  vicinity  of  the  mine. 

The  geology  of  New  Hampshire  has  been  mapped  and  the  rocks 
described  by  C.  H.  Hitchcock.'^  In  the  geologic  atlas  accompanying 
his  report  the  rocks  inclosing  the  copper  deposits  are  mapped  as  the 
Lyman  group,  a  belt  of  which  3  or  4  miles  wide  extends  from  a  point 
2  miles  south  of  the  Milan  mine  northward  toward  the  Canadian 
boundary.  A  belt  of  the  same  rocks  separated  from  the  first  by 
intruding  j)orphyry  extends  southwestward  50  miles  or  more  beyond 
Woodville.  The  latter  belt  includes  the  mines  of  the  Ammonoosuc 
district,  which  have  been  worked  for  copper,  gold,  and  silver.  The 
deposits  of  these  mines,  to  judge  from  the  descriptions  of  the  ores, 
have  many  features  in  common  with  the  deposits  at  Milan. 

The  rocks  mapped  by  Hitchcock  as  the  Lyman  group  are  mainly 
quartzites  and  siliceous  chloritic  schists,  which  were  regarded  by  him 
as  upper  Huronian.  They  are  in  the  main  siliceous  sedimentary 
rocks  intensely  metamorphosed.  On  either  side  of  this  belt  are  areas 
equally  long  and  wider,  which  Hitchcock  mapped  as  the  Lisbon 
group.     These  two  groups  of  rocks  are  intimately  interfolded  and 

"  Geology  of  New  Hampsbire,  vols.  1  to  3. 


MILAN    MINE,    NEW    HAMPSHIRE.  53 

presumabh^  have  about  the  same  age  and  origin.  Southeast  of  the 
Milan  mine,  including  the  area  of  the  Milan  Hills  and  extending 
southward  beyond  Berlin,  is  an  area  mapped  by  Hitchcock  as  "  Lake 
and  Granitic  gneiss."  The  contact  relations  with  the  Huronian  rocks 
are  not  given,  but  this  gneiss  is  presumably  in  part  a  regionally 
metamorphosed  granite,  the  age  of  which  is  not  known. 

The  top  of  the  Huronian  series  is  the  auriferous  conglomerate  which 
is  exposed  at  many  places  in  New  Hampshire.  It  contains  pebbles 
of  jasper,  schists,  and  quartz  and  has  been  greatly  metamorphosed. 
It  carries  locally  from  40  cents  to  $2  a  ton  in  gold,  but  it  is  not  clear 
whether  the  gold  is  a  clastic  constituent  or  was  introduced  after  the 
formation  was  deposited;  the  presence  of  quartz  pebbles,  how- 
ever, suggests  the  possibility  of  mineralization  prior  to  regional 
metamorphism. 

The  country  rock  at  the  mine  is  a  highly  metamorphosed  siliceous 
schist.  In  the  underground  workings,  which  do  not  go  far  into  the 
country  rock,  it  shows  neither  quartzites,  limestones,  or  conglomerate 
layers,  nor  grains  of  grit,  bedding  planes,  or  other  characteristics  of 
sedimentary  rocks  that  would  indicate  its  clastic  character.  It  has 
well-defined  planes  of  schistosity,  which  near  the  mine  strike  north- 
ward and  dip  from  30°  W.  to  90°.  Locally  they  dip  eastward  at 
very  high  angles.  The  microscope  shows  the  schist  to  be  composed 
of  quartz,  chlorite,  biotite,  muscovite,  and  pyrite.  The  quartz  grains 
are  oriented  parallel  to  the  mica  and  chlorite  flakes. 

On  the  surface,  perhaps  one-fourth  mile  northwest  of  the  mine  and 
between  the  mine  and  the  railroad  track,  beds  of  highly  siliceous  schist 
outcrop  at  many  places.  Some  of  these  rocks  contain  a  myriad  of 
thin  dark  actinolite  fibers.  Where  subjected  to  weathering  the 
siliceous  schist  shows  the  rounded  sand  grains  of  a  fine  quartzite. 
The  wall  rock  of  the  mine  is  less  siliceous  than  the  quartzite  and 
contains  a  greater  percentage  of  chlorite,  biotite,  and  muscovite. 
Mineralogically  the  wall  rock  is  such  as  may  have  resulted  from  the 
intense  regional  metamorphism  of  a  quartz-rich  shale  or  clayey 
quartzite,  and  there  is  nothing  inconsistent  with  a  sedimentary  origin 
in  its  general  appearance  and  mineralogical  composition. 

J.  W.  Huntington,*  of  the  New  Hampshire  Geological  Survey, 
describing  the  area  near  Milan,  says : 

The  railway  cuts  the  gray  siliceous  schist  in  the  east  part  of  Stark,  in  the 
corner  of  Dummer,  and  at  several  places  for  a  mile  east  of  West  Milan.  East- 
erly dips  prevail  on  the  west  and  westerly  dips  prevail  on  the  east,  so  as  a 
whole  it  seems  to  be  a  synclinal  axis  with  minor  folds  near  the  middle  of  the 
area.  The  rocks,  except  the  hard  siliceous  schists  on  the  west,  we  have  placed 
in  the  Lyman  group,  which  is  the  upper  member  of  the  Huronian. 

«  Hitchcock,  C.  H.,  Geology  of  New  Hampshire,  vol.  2,  1877,  p.  201. 


54 


SOME    OEE    DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 


From  these  observations  it  seems  that  the  Milan  mine  is  on  the 
east  limb  of  the  synclinal  axis  formed  by  the  schistosity.  A  cross 
section  taken  from  the  New  Hampshire  atlas  is  shown  as  figure  19. 

On  the  115-foot  level  of  the  mine,  about  35  feet  northwest  of  the 
shaft,  there  is  about  3  feet  of  an  actinolitic  schist  which  is  different 
in  appearance  and  mineralogical  composition  from  the  biotite  schist 
that  constitutes  the  walls  at  most  places.  It  consists  of  a  dark, 
fine-grained  groundmass  containing  abundant  crj^stals  of  hornblende 
about  1  mm.  thick  and  1  cm.  long.    Under  the  microscope  the  horn- 


,  Stark 
Porphyry   rPercyPd.. 


corpnyry 


I 


Androscoggin,  R. 
Lisbon  I 

group 


Lyman  group 


/         /   Lake  gneiss       \        Lisbon  group 


OvicKwolnepy  Str. 


FiGUEB   19. — Geologic  east-west  cross  section  through  West  Milan,  N.   H.,   north  of  the 
Milan  copper  mine.      (After  Hitchcock,  Atlas  of  New  Hampshire,   1878.) 

blende  shows  characteristic  cleavage  and  is  surrounded  by  a  ground - 
mass  of  fine  quartz  and  clouded  sericitic  bodies,  which  are  probably 
decomposed  feldspars.  It  contains  also  some  chlorite,  magnetite,  and 
calcite.  This  rock  appears  to  be  more  basic  than  the  biotite  schist 
and,  to  judge  from  its  relations  with  the  schist,  it  is  probably  the 
metamorphosed  product  of  a  dike  of  diabasic  or  more  acidic  compo- 
sition— a  dike  which  cut  the  siliceous  country  rock  before  that  rock 
was  metamorphosed. 

MINERALS    OF    THE    ORE. 

The  deposits  are  overlapping  pyritic  lenses  parallel  to  the  schis- 
tosity of  the  country  rock.  The  gangue  is  quartz,  chlorite,  black 
mica,  and  white  mica.     The  sulphides  are  pyrite,  chalcopyrite,  zinc 

blende,  galena,  bor- 
nite,  and  chalcocite. 
Little  or  no  mag- 
netite is  present  and 
pyrrhotite  was  not 
noted  in  several  tests 
that  were  made.  In 
a  list  of  minerals  of 
New  Hampshire, 
published  in  1886,*^ 
however,  it  is  men- 
tioned as  occurring 
in  the  ore.  The  ore  carries  $1.50  in  gold  and  about  1  ounce  of 
silver  to  the  ton.  Much  of  the  ore  is  solid  pyrite,  which  includes 
fragments  of  the  banded  schists  oriented  parallel  to  the  walls. 
Here  and  there  the  pyrite  is  cut  by  white  quartz  stringers,  as  is 


Figure  20. — Pyrite  cut  by  quartz,  Milan  mine. 
6,  pyrite. 


a.  Quartz ; 


»  Mineral  Resources  U.  S,  for  1885,  U.  S.  Geol.  Survey,  1886,  p,  757. 


MILAN    MINE,    NEW    II  AM  PS  1 1  IKE. 


DO 


shown  in  figure  20.  Some  of  the  sulphide  ore,  notiibly  in  the 
crosscut  to  the  west  at  the  south  end  of  the  115-foot  level,  is  massive 
zinc  blende,  carrying  well-formed  crystals  of  pyrite  1  mm.  in  diame- 
ter, with  here  and  there  small  specks  of  galena.  In  the  stope  at  the 
north  end  of  the  115-foot  level  and  between  the  115-foot  level  and  the 
70-foot  level  above  the  main  ore  body,  a  mass  of  white  quartz  is  cut 
by  veinlets  of  galena  and  pj^rite  and  has  specks  of  those  minerals 
scattered  through  it.  Below  this  ore  the  vein  consists  of  i:)yrite  and 
chalcopyrite  cut  by  innumerable  fracture  planes  which  are  filled 
with  paper-thin  films  of  chalcocite,  the  whole  carrying  12  per  cent  of 
copper.  An  oxidized  seam  with  C  inches  of  limonitic  material  is 
above  this  body  of  copper  ore,  and  this  appears  to  have  been  a  water- 
course which  was  followed  by  the  downward  circulation  of  sulphate 
waters  which  deposited  chalcocite  and  bornite  films  on  the  chalcopy- 
rite. This  ore,  Mdiich  carries  more  of  the  primary  chalcopyrite  than 
the  mine  run,  is  also  richer  in  gold.  Some  of  it  carries  as  much  as 
one-fourth  ounce  to  the  ton.     A  cross  section  of  the  vein  at  this  place 


sw 


10  Feet 


Figure  21. — Section  of  vein  at  east  end  of  115-foot  level,  40  feet  above  floor,  Milan  mine. 
a,  Oxidized  streak  ;  h,  schist ;  c,  massive  quartz,  pyrite.  and  galena  ;  d,  pyritiferous  schist 
or  milling  ore  ;   e,  massive  pyrite. 

is  shown  in  figure  21.  The  lode  is  at  no  place  completely  oxidized, 
but  in  the  slopes  40  feet  below  the  surface  limonite  in  seams  and 
copper  carbonate  and  sulphate  were  noted  at  many  places  along  nar- 
row fractures.  Locally  the  sulphide  ore  extends  to  the  grass  roots, 
with  only  a  light  veneer  a  fraction  of  an  inch  thick  where  it  is 
exposed  to  the  air. 

ORE  BODIES. 


The  ore  bodies  are  two  overlapping  lenses  separated  by  10  or  15 
feet  of  biotite  schist.  They  strike  a  few  degrees  east  of  north  and 
dip  steeply  westward.  They  are  not  tabular  but  broadly  they  ap- 
proach that  form.  In  detail,  however,  they  are  characterized  by  gen- 
tle undulations  along  both  the  dip  and  the  strike  and  at  some  places 


56 


SOME   OKE   DEPOSITS  IIST   MAINE  AND   NEW    HAMPSHIRE. 


there  are  turns  of  more  than  45°  along  both  dip  and  strike.  The  south 
ore  body  outcropped  on  the  present  site  of  the  mill  and  the  mine  was 
first  worked  in  an  open  cut  from  15  to  25  feet  wide,  which  extends 
200  feet  along  the  strike.  At  a  depth  of  70  feet  a  shaft  was  sunk 
and  stopes  in  both  ore  bodies  were  carried  wp  to  that  level.  The 
south  ore  body  as  developed  is  from  5  to  25  feet  wide  and  like  the 
north  ore  body  it  dips  steeply  westward.  Near  the  surface  it  is 
developed  southward  for  275  feet  along  the  strike.  At  its  northern 
termination  the  end  of  the  ore  pitches  southward  at  a  low  angle. 

On  the  70-foot  level  it  is  45 
feet  from  the  shaft  and  dips 
toward  it  from  50°  to  70°, 
becoming  steeper  in  depth. 
Near  the  end  of  this  lens, 
at  the  pump  station  below 
the  115-foot  level,  the  ore  is 
highly  crumpled. 

The  north  ore  body  is  de- 
veloped northward  550  feet 
along  the  strike  and  it  is 
approximately  15  feet  wide. 
The  south  end  of  the  north 
ore  body  on  the  115-foot 
level  is  encountered  in  a 
short  crosscut,  40  feet 
southwest  of  the  shaft.  It 
has  been  followed  N.  20° 
E.  for  a  distance  of  360 
feet,  where  it  bends  to  due 
north,  keeping  the  course 
for  120  feet.  At  chute  No. 
2  it  turns  at  an  angle  of 
?       .       ,       ,        ,      50 Feet.  40°^  striking  N.  40°  E.  for 

Figure  22. — Cross  section  of  ore  bodies,  Milan  mine.     ^5   feet.      A  crOSS  SCction  of 

the  two  ore  bodies  35  feet  south  of  the  shaft  is  shown  in  figure  22, 
and  a  plan  of  the  115-foot  level  in  figure  23. 

From  a  point  near  the  east  end  of  the  115-foot  level  and  about  40 
feet  up  in  the  slope  the  section  of  the  lode,  which  here  dips  40°  NW., 
shows  4  feet  of  massive  pyrite  above  a  foot  wall  of  chloritic  quartz 
schist.  Above  this  is  6  feet  of  pyrite  and  quartz  with  a  little  mica,  all 
highly  schistose,  the  planes  following  the  orientation  of  the  lode. 
Above  the  latter  is  a  mass  of  quartz  about  3  feet  thick,  with  seams  of 
pyrite  and  galena.  Near  the' center  of  the  6  feet  of  pyrite  and  quartz 
which  constitute  a  milling  ore  there  is  a  seam  of  highly  oxidized  ore 


MILAN    MINE,    NEW    nAMPSHIRE. 


57 


along  a  plane  of  movement.     This  plane  is  clearly  a  postmineral 

fissure.       A     few     feet    lower    this 

fissure   departs   from  the  ore  body, 

keeping-  its  regular  course  while  the 

ore     body     turns,     striking     nearly 

northeastward  and  dipping  steeply. 

Where  noted  in  a  drift  below  it  is 

vertical  and  at  one  place  overturned. 

The  ore  bodies  are  parallel  to  the 
schistosity.      At    some    places    the 
walls    are    intensely    crumpled    and 
much  of  the  milling  ore  consists  of 
the  thin  alternating  bands  of  schist 
and    pyrite    intimately    interbanded 
and  crenulated.     These  seams  of  py- 
rite and  quartz  are  also  parallel  to 
the    schistosit}^,    and    as    shown    by     S 
Plate  III,  A,  are  clearlj^  metamor-     § 
phosed  by  the  same  crumpling  move-     li 
ments.      The     ore     is     undoubtedly     J^ 
older  than  the  metamorphism  of  the     g 
schists.     At  many  places  it  grades     a 
into  the  pure  massive  pyrite  ore,  but     m 
the  latter  does  not  show  any  schis-     g" 
tosity.     There  is  no  noticeable  seri-     ^ 
citization     or     other    hydrothermal     | 
metamorphism  of  the  walls  nor  any     "^ 
leaching  of  the  wall  rock,  such  as  is     ^ 
characteristic  of  most  ore  bodies  not     g 
regionally  metamorphosed,  and  the     g 
ore  at  no  place  shows  comb  struc- 
ture, crust ification,  or  druses. 

The  i^tan  of  the  115-foot  level 
illustrates  further  the  eifects  on  the 
ore  body  of  the  regional  metamor- 
phism due  to  intense  shearing  move- 
ments under  load  which  develoj)  the 
schistose  structure  in  the  country 
rock.  Before  shearing  the  ore  body 
was  probably  a  single  tabular  mass, 
but  by  these  movements  it  was 
thrust  endwise  upon  itself,  so  that 
it  divided  and  overlapped.  The  di- 
vision can  hardly  be  called  a  fault 
in  the  common  sense,  since  it  took 
place  in  the  zone  of  flow  for  the  schist  and  was  a  pulling  apart,  not 


w 

'ill 

Mm 


58  SOME    OEE   DEPOSITS   IN    MAINE   AND    NEW    HAMPSHIRE. 

by  a  sharp  cleavage,  but  rather  as  a  somewhat  viscous  body  is  divided. 
A  tight  fissure  dipping  westward  at  about  the  same  angle  as  the  two 
ore  bodies  joins  the  two  ends  and  wraps  around  the  ore  at  both  termi- 
nations. The  schistosity  likewise  wraps  around  the  ends  of  these  ore 
bodies  and  parallels  the  fissure  which  joins  them.  These  features  are 
shown  in  figure  23.  This  relationship  of  the  schistosity  to  the  line  of 
movement  which  separates  the  two  lenses  shows  that  the  ore  body  has 
been  subjected  to  the  same  earth  movements  as  the  rock.  Since  it  has 
separated  in  the  zone  of  flow  it  must  have  been  deposited  before  regional 
metamorphism.  This  is  further  indicated  by  the  gradation  of  the  mas- 
sive i^yrite  ore  into  pyrite  containing  parallel  quartz  and  mica  bands, 
of  this  into  quartz  biotite  with  numerous  thin  bands  of  pyrite,  and  of 
this,  again,  into  schist  with  only  an  occasional  band  of  pyrite  and  this 
into  nearly  pure  schist.  Thus  the  rock  shows  bands  of  the  schist  and 
bands  of  the  pyrite  varying  in  all  proportions  along  the  wall,  and 
the  ore  always  shows  the  minutely  schistose  structure  wherever  it 
contains  quartz  and  biotite.  The  main  lode  of  pyrite  ore  has  ex- 
actly the  same  character  as  the  smaller  massive  layers  and  must 
have  the  same  origin,  but  where  pure  and  large  it  is  as  free  from 
conspicuous  marks  denoting  movement  as  any  ore  deposit  in  un- 
metamorphosed  rock.  Some  of  the  crystals  of  pyrite  have  perfect 
form  when  included  as  the  thinnest  seams .  between  the  quartz-rich 
or  biotite-rich  layers  of  the  schist.  As  these  pyrite  seams  increase  in 
size  and  purity  they  become  more  massive,  and  where  silica  minerals 
are  absent  the  ore  does  not  show  any  lamination  parallel  to  the  schis- 
tosity of  the  country  rock,  although  the  ore  is,  without  doubt,  older 
than  the  final  metamorphism  of  the  schist  and  partook  in  its  move- 
ments. The  aluminous,  more  or  less  plastic  wall  rock  was  capa- 
ble of  crumpling  to  gnarly  schistose  layers,  and  where  the  seams 
of  pyrite  alternate  with  thin  seams  of  quartz  the  same  schistosity 
is  shown;  but  massive  pyrite  ore  not  containing  quartz  or  clayey 
material  adjusts  itself  to  conditions  of  pressure  without  leaving  a 
conspicuous  record  of  the  movements.  The  pure  pyrite  is  at  no  place 
laminated.  The  larger  pyrite  bodies  have  broken  and  have  been  re- 
cemented  by  pyrite  and  the  smaller  crystals  have  completely  recrystal- 
lized,  mainly  into  small  cubic  and  octahedral  crystals  rather  than  into 
l^yritohedrons. 

Galena  and  zinc  blende  have  also  recrystallized.  Some  of  the  chal- 
copyrite  shows  faint  lamination,  a  feature  of  chalcopyrite  noted  also 
in  the  Tapley  mine  at  Brooksville,  Me. 

The  ore  bodies  are  believed  to  be  tabular  deposits  of  sulphide  ore 
metamorphosed  by  the  same  movements  that  converted  the  highly 
quartzose  shales  into  quartz-biotite  schists.  It  is  remarkable  that 
this  lode,  like  most  of  the  members  of  the  class,  should  every- 
where be  approximately  parallel  with  the  schistosity  of  the  country 


MILAN    MINE,    NEW    IIAMPSHIKE.  59 

rock.  Ore  bodies  in  a  given  district  of  unnietainorphic  rocks  very 
often  present  a  great  variety  of  dips  ;uid  strikes,  and  in  many  districts 
there  are  two  vein  systems  nearly  at  right  angles  to  each  other.  The 
movement  causing  the  schistosity  is  apparently  controlled  to  some 
extent  by  the  ore  bodies  or  else  the  ore  bodies  are  rotated  to  conform 
to  the  general  movements  as  recorded  in  the  structure  of  the  schists. 
Probably  the  agreement  of  ore  with  schistosity  is  brought  about  in 
both  Avays.  First,  the  pyrite  bodies  are  broken  and  the  parts  tend 
to  orient  themselves  at  right  angles  to  the  line  of  pressure,  as,  for 
example,  the  flat  or  oblong  grains  of  sand  in  a  quartzite  or  quartz 
schist,  or  as  the  mica  flake  in  a  mica  schist ;  and,  second,  the  schistos- 
ity of  the  walls  is  probably  controlled  locally  by  the  large  masses 
of  ore  if  the  ore  body  is  too  immobile  to  orient  itself  to  conform  with 
new  conditions  of  pressure  as  do  the  oblong  quartz  particles  in  the 
quartzose  shale  when  it  is  metamorphosed  to  biotite  schist. 

At  the  south  end  of  the  north  ore  body  on  the  115-foot  level  the  ore 
is  highly  siliceous  and  consists  of  intensely  crumpled  pyrite  and 
quartz.  At  this  place,  where  the  ore  body  pulled  apart  and  became 
two  lenses,  the  ore  looks  like  a  surface  of  gnarled  oak  or  vermicelli. 
Here  the  schistosity  of  the  walls  instead  of  striking  northward 
parallel  to  the  main  lode  strikes  westward  parallel  to  the  end  of  the 
lens.  On  an  intermediate  level,  just  below,  near  the  pump  station, 
the  same  intense  crumpling  is  shown  at  the  north  end  of  the  south 
ore  body. 

These  places  show  that  the  ore  body  broke  where  it  was  most 
siliceous  and  most  heterogeneous  and  because  of  that  hetero- 
geneity of  composition  the  movement  was  best  recorded.  If  it  had 
been  pure  pryite  instead  of  quartz-pyrite-chlorite  ore  it  would  not 
have  shown  the  intense  crumpling,  foi  the  pyrite  would  have  broken 
and  recemented  into  an  apparently  homogeneous  mass.  Since  the 
broken  end  of  the  south  ore  body  pitches  toward  the  south,  with  the 
ore  on  the  foot  wall  of  the  pitch,  it  should  be  expected  that  the  broken 
end  of  the  north  ore  body  should  also  pitch  to  the  south,  with  the 
ore  on  the  hanging  wall  of  the  pitch. 

SUMMARY   OF   THE   GENESIS. 

The  deposit  was  at  one  time  a  large  mass  of  ore  contained  in  impure 
quartzite  or  slate  which  if  metamorphosed  was  less  intensely  metamor- 
phosed than  at  the  present  time.  The  ore  may  have  been  deposited  at 
the  time  the  granular  rocks  mapped  by  Hitchcock  as  "  Lake  and  Gra- 
nitic gneiss  "  were  erupted  or  at  the  time  of  the  intrusion  of  a  basic 
igneous  rock  which  is  now  actinolite  schist.  It  was  not,  however,  a 
contact-metamorphic  deposit,  for  it  has  none  of  the  characteristics  of 
such  deposits  and  it  does  not  contain  garnet  and  epidote  and  other 
lime  silicates  which  are  usually  found  in  such  deposits.    Presumably 


60  SOME    ORE   DEPOSITS   IN    MAINE   AND   NEW    HAMPSHIBE. 

it  was  first  formed  at  moderate  depth  and  then  consisted  of  quartz, 
pyrite,  zinc  blende,  galena,  chalcopyrite,  and  some  aluminous  mate- 
rial— either  clay  or  sericite;  the  walls  were  presumably  replaced  by 
pyrite  and  other  minerals.  After  deposition  it  was  deeply  buried 
and  was  intensely  deformed  in  the  zone  of  flow  at  the  time  when 
the  siliceous  shales  were  subjected  to  regional  metamorphism  and 
changed  to  schists,  or  at  the  latest  before  this  process  had  ceased  to 
operate.  During  the  process  of  metamorphism  the  deposit  was  de- 
formed by  pressure.  Certainly  it  was  pulled  apart  at  one  place  and 
thrust  back  on  itself  so  that  the  two  ends  overlapped  some  40  feet. 
The  ore  body  pulled  apart  where  it  was  most  siliceous,  where  parallel 
sheets  of  quartz  and  mica  are  abundant  in  the  pyrite,  and  because 
of  this  circumstance  of  heterogeneity  also  a  maximum  of  squeezing 
and  crumpling  was  recorded.  The  sulphides  were  crushed,  re- 
cemented,*  and  at  some  places  dissolved  and  reprecipitated.  Drusy  cav- 
ities and  banded  and  comb  structures,  if  present,  were  destroyed.  Any 
evidences  of  hydrothermal  metamorphism  along  the  walls  of  the 
deposit  were  obscured  by  the  subsequent  regional  metamorphism  of 
the  deposit  and  the  country  rock.  After  metamorphism  the  rock 
above  the  deposit,  probably  a  considerable  thickness,  was  eroded 
away,  and  minor  movements  resulted  in  fractures  and  slickensided 
planes,  cutting  the  lode  approximately  parallel  to  the  dip  and  strike. 
Ultimately  through  water  and  glacial  erosion  the  present  outcrop  of 
the  deposit  was  exposed.  Descending  sulphate  waters  deposited  a 
little  chalcocite  in  the  later  fractures.  The  lode  was  partly  oxidized 
at  the  outcrop,  but  at  most  places  the  oxides  did  not  extend  more  than 
40  feet  below  the  surface  and  at  some  places  near  the  surface  they 
scarcely  formed  at  all. 


INDEX. 


Page. 

Acknowledgments  to  those  aiding 8 

Amos  Knob  formation,  occurrence  and  char- 
acter of 12-13 

Bastin,  E.  S.,aidof 8,11 

Battie  quartzite,  occurrence  and  character  of.  12 

Bibliography 8-10 

Blue  Hill  mine,  description  of 33 

ores  of 16, 19, 33 

vicinity  of,  geologic  map  of 30 

Brookville,  copper  near 16 

Cape  Rozier  mine,  description  of 38 

ores  of - 19, 38 

Castine  formation,  occurrence  and  character 

of 13 

ores  in 15-16 

Catherine  Hill  mine,  description  of 42 

ores  of 21,42 

figure  showing 42 

Cherryfield  mine,  description  of 43 

Coast,  outcrops  on 25 

Concord  mine,  ores  of 21 

Cooper  mine,  ores  of 47 

Copper  ores,  age  of 15 

deposits  of 16-19, 22 

mining  of 11, 16, 27, 31-32, 34-38, 41, 46-47 

production  of 11 

Copperopolis  mine,  description  of 41-42 

Deer  Isle  mine,  description  of 37-38 

ores  of 19, 20, 27, 38 

figures  showing 20 

Denbow  Point  mine,  description  of 45 

ores  in 22, 45 

Diabase,  ores  associated  with 22 

Dikes,  occurrence  and  character  of 15 

Diorite,  occurrence  and  character  of 15 

Douglas  mine,  description  of 31-32 

development  at 11 

ores  in 26 

analysis  of 32 

Eggemoggin  mine,  description  of 36-37 

Ellsworth  schist,  occurrence  and  character 

of 11-12 

ores  in 15-16 

Emerson  mine,  description  of 39 

ores  of 19, 39 

Enrichment,  secondary,  eflects  of 26 

Field  work,  extent  of 8 

Fissure  veins,  occurrence  and  character  of . . .  20-21 

Franklin  Extension  mine,  description  of 41 

Geography,  character  of 10 

Geology,  outline  of 11-15 

See  also  particular  counties. 


Glaciation,  effects  of 24-25 

Gouldsborough  mine,  description  of 40-41 

ores  of 21,41 

Granger  mine,  description  of 35 

Granite,  occurrence  and  character  of 14-15 

ore  deposits  associated  with 20-22 

Hancock  County,  geology  of 30-31 

mines  in,  description  of 31-42 

Hercules  mine,  description  of 38 

ores  of - 19,38 

Hess,  F.  L.,  on  Cooper  mine 47 

Hitchock,  C.  H.,  on  Milan  mine 62-53 

Huntington,  J.  W.,  on  Milan  region 53 

Iron,  mining  of 7, 10 

Islesboro  formation,  occurrence  and  charac- 
ter of 12 

Jackson,  C.  T.,  cited 10 

Jewel  Island,  mining  on 10 

Jones  &  Dodge  mine,  description  of 38 

Kempton,  C.  W.,  on  Sullivan  mine 40 

Lava,  occurrence  and  character  of 15 

Lead  ores,  age  of 15 

deposits  of 21-22 

mining  of 10, 2&-27, 32-35, 37, 41, 43-45 

Lindgren,  Waldemar,  aid  of 8 

Literature,  list  of 8-10 

Lubec,  lead  at 10 

Lubec  mine,  description  of 44-45 

ores  in 22, 44-45 

figures  showing 44, 45 

Maine,  southern,  map  of 7 

mines  in,  descriptions  of 30-50 

Mammoth  mine,  description  of 34 

Map  of  southern  Maine 7 

Metals,  occurrence  of 7 

production  of 11 

Metamorphism,  effects  of 18-20 

occurrence  and  character  of 28 

time  of,  relation  of  ore  deposits  and 15 

Milan  mine.  New  Hampshire,  description  of. .    8, 50 

faulting  in 29, 50 

genesis  of 59-60 

geology  of 50, 52-54 

minerals  in 54r-55 

ores  of 16-17, 26, 50-52, 55-59 

analysis  of 51, 52 

figures  showing 17, 19, 42, 54, 55, 56 

plan  of,  figure  showing 57 

section  near,  figure  showing 54 

Mineralogy,  data  of 22-24 

Mines,  description  of 30-60 

future  of 26-27 

61 


62 


INDEX. 


Page 

Mining  development,  extent  of 10-11 

Molybdenite,  mine  of 42, 47-49 

occurrence  and  character  of 21 

plate  showing 42 

Mount  Glines,  description  of 49-50 

Mount  Katahdin,  iron  on 10 

North    Haven    greenstone,  occurrence    and 

character  of 13-14 

Ore  deposits,  age  of,  relation  of,  to  metamor- 

phism 15 

classification  of 15-22 

distribution  and  character  of 15-18 

figures  showing 17, 18, 19, 20, 21, 22 

geologic  history  of 27-30 

metamorphism  of 18-20 

mineralogy  of 22-24 

origin  of 20 

outcrops  of 24-25 

oxidation  of 25-26 

Sec  also  Metals;  Mines. 

Outcrops,  distribution  of 24-25 

Owen  lead  prospect,  description  of 34-35 

ores  of,  figure  showing 20 

Owen  mine,  description  of 34 

ores  of 21, 34 

Oxford  County,  deposits  at 49-50 

Oxidation,  effects  of 25-26 

Pembroke,  ores  of 22, 46-47 

ores  of,  figures  showing 22, 46 

Penobscot  formation,  occurrence  and  char- 
acter of 12 

Perry  formation,  occurrence  and  character 

of 13 

Pine  Tree  mine,  location  of 39 

Production  of  metals,  data  on 11 


Page. 

Pyrite,  mining  of lo 

Robinson,  F.  C,  aid  of 8 

Robinson  mine,  description  of 48-49 

ore  of 49 

figure  showing 49 

plan  of,  figure  showing 48 

Seacoast,  outcrops  on 25 

Silver  ores,  age  of 15 

deposits  of 19-20, 22 

mining  of 11, 26-27, 36-37, 39-41, 43, 45 

production  of 11 

Smith,  G.  O.,  aid  of ; 8, 11 

Somerset  County,  mines  of,  description  of 48-49 

Stewart  mine,  description  of 33-34 

Stone,  quarrying  of IQ 

Sullivan  mine,  description  of 39-40 

ores  in 20-21, 40 

figures  showing 21-39 

Tapley  mine,  description  of , 35-36 

ores  at 16,36 

figure  showing 16 

Thorofare  andesite,  occurrence  and  character 

of 14 

Twin  Lead  mine,  description  of 32-33 

ores  in 16, 33 

figures  showing 17, 18 

Vinalhaven  rhyolite,  occurrence  and  char- 
acter of 14 

Washington  County,  geology  of 43 

mines  in,  descriptions  of 43-48 

Waukeag  mine,  description  of 39 

Weil  Freddie  mine,  description  of 35 

Zinc  ores,  age  of 15 

deposits  of 19, 20, 21 

mines  of 26-27, 34-39, 41, 43 


o 


DATE  DUE 


OCT  2- 

L2Q06— 



UNIVERSITY  PRODUCTS,  INC.    ffW«-oouo 


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BOSTON   COLLEGE 


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